Motion Sensor for Occupancy Detection and Intrusion Detection

ABSTRACT

A motion sensor has an infrared detector with a first set of detector elements coupled to a first channel and a second set of detector elements coupled to a second channel. A first optical subsystem directs infrared radiation from a first number of monitored volumes to the infrared detector and a second optical subsystem directs infrared radiation from a second number of monitored volumes to the infrared detector. Intrusion detection circuitry is coupled to both channels of the infrared detector and selects a set of peaks in the first channel and the second channel. It then calculates an alternation score based on a number of alternating peaks in the set of peaks, and indicates an intrusion detection based, at least in part, on the alternation score. The circuitry also determines a peak-to-peak period for the first channel and calculates a slope-synchrony measurement to modify the alternation score.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International PatentApplication PCT/US2017/019414, entitled Motion Sensor for OccupancyDetection and Intrusion Detection, filed Feb. 24, 2017, which claimspriority to U.S. Provisional Patent Application No. 62/299,111, entitledMotion Sensor for Occupancy Detection and Intrusion Detection, filed onFeb. 24, 2016. This patent application is also related to InternationalPatent Application PCT/US2013/073799 published on Jun. 18, 2015 asWO2015/088470A1, entitled MOTION DETECTION, and International PatentApplication PCT/US2015/030692 published on Dec. 10, 2015 asWO2015/187326A1, entitled MOUNT FOR SECURITY DEVICE. The entire contentsof all of the above-mentioned Patent Applications are herebyincorporated by reference for any and all purposes.

BACKGROUND Technical Field

The present subject matter relates to motion detection. Morespecifically it relates to multi-output infrared radiation detectors andmotion sensors using such an infrared detector.

Background Art

Motion Sensors utilizing infrared radiation detectors, or simply IRdetectors, are well known. Such sensors are often used in securitysystems or lighting systems to detect movement in a monitored space. Aninfrared detector detects changes in mid-infrared (IR) radiation havinga wavelength of about 6-14 microns. These changes are due to temperaturedifferences between a warm object, such as a warm blooded animal, andits background environment as the warm object moves through thatenvironment. Upon detection of motion, motion sensors typically activatean audible alarm such as a siren, turn on a light, and/or transmit anindication that motion has been detected.

A typical IR detector utilizes a pyroelectric or piezoelectric substratewith a detector element that consists of conductive areas on oppositesides of the substrate, acting as a capacitor. As the substrate changestemperature, charge is added to or subtracted from the capacitor,changing the voltage across the capacitor. The amount of mid-IRradiation that hits the detector element determines the temperature ofthat area of the substrate, and therefore, the voltage across thecapacitor that makes up the detector element. Some motion sensorsutilize an infrared detector that includes multiple detector elements.To reduce the chance of false alarms, some infrared detectors include apair of equally sized detector elements of opposing polarities.Non-focused out-of-band radiation, as well as ambient temperaturechanges or physical shock, is equally incident on both detectorelements, thus causing the signals from the equal and opposite elementsto roughly cancel one another.

Many motion sensors incorporate an optical array (made of opticalelements, such as lenses, focusing mirrors, and so on) to be able tomonitor a large space with a single infrared detector. The optical arraydirects the IR radiation from multiple monitored volumes onto theinfrared detector, and sometimes includes filters to minimize theradiation outside of the desired mid-infrared range from reaching theinfrared detector. Each of the monitored volumes is typically apyramidal shaped volume extending into the space to be monitored withthe apex of the pyramid at the motion sensor. Concentrations ofradiation from each of the pyramids are projected by the optical arrayson to the infrared detector where they are superimposed, and differentregions of the infrared detector are heated based on the amount of IRradiation received from the superimposed projections. The detectorelements on the infrared detector react to the localized heating bychanging their voltage. The resultant change in voltage across thedetector elements is monitored and used to detect motion in the spacebeing monitored.

While a motion sensor can be used for either occupancy detection or fordetection of an intruder, the two uses have very different requirements.For intrusion detection, while effective detection of a human movingthrough a volume of interest is important, false detections can lead tonegative consequences ranging from annoying alarm sirens that need to beturned off, to financial consequences from summoning the police too manytimes. So a motion sensor for intrusion detection needs to have goodsensitivity while having a very high rejection of possible false alarmsources such as pets moving through a room. An occupancy sensor,however, has a very different use model. The consequences for turning alight on for falsely determining a room is occupied are very minor,perhaps a few pennies for electricity that wasn't really needed. But ifa person is in a room and the lights repeatedly go off because theoccupancy detector does not register the movement, the occupant islikely to become frustrated. This means that a motion sensor foroccupancy detection needs to be very sensitive to small movements, but arelatively high rate of false alarms can be tolerated.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof the specification, illustrate various embodiments of the invention.Together with the general description, the drawings serve to explain theprinciples of the invention. They should not, however, be taken to limitthe invention to the specific embodiment(s) described, but are forexplanation and understanding only. In the drawings:

FIG. 1A shows an embodiment of a motion sensor;

FIG. 1B shows a cut-away view of the motion sensor of FIG. 1A.

FIGS. 2A and 2B are a front and rear view of an embodiment of aninfrared detector;

FIG. 2C is a schematic of the embodiment of the infrared detector ofFIG. 2A/B;

FIG. 2D is an isometric view of an embodiment of a packaged version ofthe infrared detector of FIG. 2A/B;

FIG. 3 shows a volume of interest in a typical room for an embodiment ofthe motion sensor;

FIG. 4 depicts the 80 fields of view created by the 20 lens elements and4 IR-detector elements of an embodiment;

FIGS. 5A and 5B show the fields of view of the motion sensor of FIG.1A/B intersecting with the volume of interest of FIG. 3;

FIG. 6 shows a top view of the fields of view shown in FIG. 4;

FIG. 7 shows a comparison of the fields of view of FIG. 6 compared toconventional motion sensor fields of view;

FIG. 8A shows sensitive minor-motion detection by the fields of view ofFIG. 6;

FIG. 8B shows pet-immune motion detection by the fields of view of FIG.6;

FIG. 9 is a block diagram of an embodiment of a motion sensor;

FIG. 10 is a high level data-flow diagram for an embodiment of a motionsensor;

FIG. 11 shows a signal-processing diagram for an embodiment of theoccupancy detection processing block;

FIG. 12 shows a signal-processing diagram for an embodiment of theintrusion detection processing block;

FIG. 13 is a flow chart of an embodiment of a peak-alternation methodfor intrusion detection;

FIGS. 14A, 14B, and 14C provide a set of flow charts for an embodimentof a peak-alternation with slope-synchrony method for intrusiondetection;

FIG. 15 is an image from an oscilloscope showing the two-channel outputof an IR detector in response to a human moving through the volume ofinterest; and

FIG. 16 is an image from an oscilloscope showing the two-channel outputof an IR detector in response to a small animal moving through thevolume of interest.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures andcomponents have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentconcepts. A number of descriptive terms and phrases are used indescribing the various embodiments of this disclosure. These descriptiveterms and phrases are used to convey a generally agreed upon meaning tothose skilled in the art unless a different definition is given in thisspecification.

Embodiments for a motion sensor are disclosed herein that candifferentiate between animals and humans for the purposes of intrusiondetection with a very low number of false intrusion detections, yetstill operate as a highly sensitive occupancy detector. The embodimentswithin are designed to employ very simple microcontroller-performedcalculation algorithms that support fast execution time in order toconserve battery life of the product in which the embodiment isprovided. In some cases, the optical realization of a motion sensorresults in fields of view that do not exclusively conform to the orderlyphase relationships as described in the published International PatentApplication WO2015/088470A1, thus potentially requiring very complexcalculation algorithms. As a method of interpreting real-sensor phaserelationships, while keeping the calculations simple, variousembodiments are disclosed herein.

Embodiments use a peak-alternation algorithm as an alternative todetailed phase interpolation and calculations for the situation shown inFIG. 6A of published International Patent Application WO2015/088470A1.Due to occupancy-detection criteria requiring a relatively constantfield of view size at heights where humans are expected, leading toasymmetric tiers of fields of view, such as a long-range tier having 9field of view sets, a mid-range tier having 7 field of view sets, and ashort-range tier having 4 field of view sets. So the fields of view insome embodiments are not vertically-aligned, leading to more complexwaveforms than the simple phase shifted waveforms that would result fromvertically-aligned fields of view. Rather than undertaking a complexprocess of wave-phase definition and measurement, some embodimentsutilize a simpler approach by identifying peak locations on each channelof the IR detector and determining if the two channels' peak occurrencesare alternating. In some embodiments an intrusion is detected if thereare M alternating peaks in a set of N adjacent peaks, where M is smallerthan N and are parameters that can be varied to tune the performance ofa motion sensor design.

Both a local minimum and a local maximum in a signal are referred to asa peak in the signal. Various embodiments can use different algorithmsto detect a peak, but in at least one embodiment, a peak is determinedby detecting that the voltage level of a signal has changed by at leasta predetermined threshold from a local maximum or minimum to providehysteresis for the peak detection.

Some embodiments use a simple method to determine when meaningful peaksare not occurring synchronously, that is, when a peak occurs primarilyas a result of single field of view occupancy such as the situationshown in FIG. 6B of published International Patent ApplicationWO2015/088470A1. With human-walk signals, both channels exhibit nominalslopes at the same time, showing high slope synchrony, whereas a pet,because it can only occupy one field of view at a time, produces signalsets with a wave-peak slope on one channel at a time, exhibiting lowslope synchrony between the channels. Low slope synchrony can be used toeliminate pet detection due to rare peak sequences that mimic human-walkpeak sequences, yet that actually arise from distinctively pet-typesignal sets having isolated peaks on separate channels. Slope synchronyis useful because it is not always feasible to evaluate and compare peakheight due to multiple-frequency peak components. Thus, instead ofevaluating height, relative slope activity can be compared between thetwo channels, to reduce false detections caused by pets even furtherthan with peak alternation alone.

Reference now is made in detail to the examples illustrated in theaccompanying drawings and discussed below.

FIG. 1A shows an embodiment of a motion sensor 100. The motion sensor100 can be mounted to a wall and detect motion in a volume of interestby sensing changes in infrared (IR) radiation emitted in a plurality ofmonitored volumes, or fields of view, that are projected onto an IRdetector.

FIG. 1B shows a cut-away view 101 of the motion sensor 100 of FIG. 1A,exposing a high resolution triple lens-array design for the motionsensor 100. This embodiment includes 20 lens elements focusing onto 4IR-detector elements of the IR detector 290, such as shown in FIG. 2D,creating 80 fields of view for the motion sensor. Other embodiments mayhave different numbers of lenses, such as different numbers of lensesper range, and/or different numbers of independent ranges. In someembodiments, the number of lenses between any two ranges share no commonfactor (i.e. are not both divisible by the same number). The structureincludes a front window with a long-range nine-lens array 110, aninterior mid-range seven-lens array 120, and an interior short-rangefour-lens array 130. The long-range lenses 110 have a comparatively longfocal length, the mid-range lenses 120 have a mid-range focal length,and the short-range lenses 130 have a comparatively short focal length.In some embodiments, the ratio of the focal lengths between ranges isabout equal to 1.414, or the square-root of 2. In at least oneembodiment, the short-range lenses 130 have a focal length of about 10millimeters (mm), the mid-range lenses 120 have a focal length of about14 mm, and the long-range lenses 110 have a focal length of about 20 mm.In some embodiments the lens arrays 110, 120, 130 are Fresnel lenses,but other embodiments may use other optical technologies to focus the IRradiation from a field of view onto the individual IR detector elementssuch as traditional convex lens, concave mirrors, or other types ofrefractive and/or reflective elements.

FIGS. 2A and 2B are a front and rear view of an embodiment of aninfrared detector 200. The infrared detector includes a substrate 201made with at least some pyroelectric material. The infrared detector 200includes a first row of detector elements 212 that includes one detectorelement 230 that includes pad 213 on the front side 210 of the substrate201 and pad 223 on the back side 220 of the substrate 201, and anotherdetector element 240 that includes pad 214 on the front side 210 of thesubstrate 201 and pad 224 on the back side 220 of the substrate 201.Note that pad 223 is opposite of pad 213 on the substrate 201, and pad224 is opposite of pad 214 on the substrate 201. The two detectorelements 230, 240 of the first row of detector elements 212 arepositioned on the substrate 201 in a row direction (horizontal in FIG.2A/B) spaced a pitch distance 231 apart. In the embodiment shown, thetwo detector elements 230, 240 are approximately the same size. Thefirst row of detector elements 212 includes at least two seriallycoupled detector elements 230, 240 coupled between the output pad 222and the output pad 225. In the embodiment shown, the detector element230 is configured to provide a positive voltage between the output pad225 and the output pad 222 in response to an increase in temperature,and the detector element 240 is configured to provide a negative voltagebetween the output pad 225 and the output pad 222 in response anincrease in temperature.

The infrared detector 200 also includes a second row of detectorelements 216 that includes one detector element 270 which includes pad217 on the front side 210 of the substrate 201 and pad 227 on the backside 220 of the substrate 201 and another detector element 280 thatincludes pad 218 on the front side 210 of the substrate 201 and pad 228on the back side 220 of the substrate 201. Note that pad 227 is oppositeof pad 217 on the substrate 201 and that pad 228 is opposite of pad 218on the substrate 201. The two detector elements 270, 280 of the secondrow of detector elements 218 are positioned on the substrate 201 in arow direction that is parallel to the first row 212 and spaced a pitchdistance 232 apart that is about the same as the pitch distance 231 ofthe first row 212. In the embodiment shown, all four detector elements230, 240, 270, 280 are approximately the same size. The second row ofdetector elements 216 includes at least two serially coupled detectorelements 270, 280 coupled between the output pad 226 and the output pad229. In the embodiment shown, the detector element 270 is configured toprovide a positive voltage between the output pad 229 and the output pad226 in response to an increase in temperature, and the detector element280 is configured to provide a negative voltage between the output pad229 and the output pad 226 in response to an increase in temperature.

In the embodiment of FIG. 2A/B, the first row of detector elements 212and the second row of detector elements 216 are substantiallynon-overlapping. Substantially non-overlapping, as used herein and inthe claims, means that more than 80% of the height (i.e. the dimensionorthogonal to the row direction, or vertical in FIG. 2A/B) of detectorelements 230, 240 of the first row 212 do not overlap with the detectorelements 270, 280 of the second row 218. The detector elements 270, 280of the second row 216 are, however, are positioned at a non-zero offset233 from the first row of detector elements 212 in the row direction(horizontal in FIG. 2A/B). The offset 233 can be characterized as apercentage of the pitch distance 231, 232. In some embodiments, thenon-zero offset is between about 5% of the pitch distance and about 95%of the pitch distance. In some embodiments, the offset 233 is about halfof the pitch distance 231, 232 and can be referred to as a quadratureoffset. In some embodiments, the offset 233 is not equal to one half ofthe pitch distance 231, 232, and the offset 233 can be referred to as anon-quadrature offset.

FIG. 2C is a schematic of the embodiment of the infrared detector 200 ofFIG. 2A/B. The first row of serially coupled detector elements 212 areshown as polarized capacitors 230, 240 to indicate the polarity ofvoltage generated by the detector element in response to an increase intemperature. The electrodes of the capacitors 230, 240 are marked withthe reference number of its corresponding pad of the detector element.So the detector element, or capacitor, 230 includes pad 223 and pad 213,and the detector element, or capacitor, 240 includes pad 214, and pad224. The first row of detector elements 212 is coupled to the output pad222 and to the output pad 225.

The second row of serially coupled detector elements 216 are shown aspolarized capacitors 270, 280 to indicate the polarity of voltagegenerated by the detector element in response to an increase intemperature. The electrodes of the capacitors 270, 280 are marked withthe reference number of its corresponding pad of the detector element.So the detector element, or capacitor, 270 includes pad 227 and pad 217,and the detector element, or capacitor, 280 includes pad 218, and pad228. The second row of detector elements 216 is coupled to the outputpad 226 and to the output pad 229. In at least some embodiments, theoutput pad 225 and output pad 229 are coupled to ground, and the outputpad 222 is a first output of the infrared detector 200, and the outputpad 226 is the second output of the infrared detector 200.

FIG. 2D is an isometric view of an embodiment of a packaged version 290of the infrared detector 200 of FIG. 2A/B. The packaged version 290includes a package 291 with the substrate 201 of the infrared detector200 mounted inside of the package 291 behind a mid-IR-transmissivewindow (or window/filter) in a way to allow external mid-IRelectromagnetic energy to affect the substrate 201 of the infrareddetector 200 while at the same time shielding the substrate 101 fromnon-mid-IR influences. The packaged version 290 includes at least oneterminal 292-299 accessible from outside of the package. In at least oneembodiment, the output terminal 292 is coupled to the output pad 222,the output terminal 295 is coupled to the output pad 225, the outputterminal 296 is coupled to the output pad 226, and the output terminal299 is coupled to the output pad 229. Some embodiments of the packagedversion 290 include circuitry, such as an analog multiplexer, analoglow-pass filter, analog-to-digital converter, or other circuitry,mounted in the package 291 and coupled between the infrared detector 200and the at least one output terminal 292-299.

FIG. 3 shows a volume of interest in a typical room 300 for anembodiment of the motion sensor. The room could be a family room, livingroom, bedroom, or any other room where an indication of occupancy or anindication that an intruder has entered is desired. In the embodiment,the motion sensor 100 is mounted 7.5 ft (2.3 m) above the floor,although depending on the room, it might be mounted at a differentheight such as 10 ft (3.0 m) with a reversible mounting bracket as shownin FIG. 9A-C, inter alia, of published International Patent ApplicationWO2015/187326A1, or at any other height above the floor depending on thegeometry of the fields of view, or monitored volumes, of the motionsensor 100 and desired volume of interest 320. In this example, thevolume of interest 320 is a volume bounded by a box with one edge in thecorner of the 20 ft×20 ft (6.1 m×6.1 m) room 300 where the motion sensor100 is located and extending out 18 ft (5.5 m) along each adjacent wallof the room 300 and covering the volume starting about 2 ft (0.6 m) fromthe floor to about 5 ft (1.5 m) from the floor. The motion sensor 100,acting as an occupancy sensor, can detect small amounts motion by a warmblooded animal, such as a human in the volume of interest 320, and senda notification that the room is occupied. The motion sensor 100, actingas an intrusion sensor, can detect a person walking through the volumeof interest 320 and send an intrusion notification while not generatingan intrusion notification for motion by small warm-blooded animals, suchas a dog or a cat moving through the volume of interest 320. In someembodiments, a small portion of the cube bounding the volume of interest320 in the corner near the motion sensor 100 may not be monitored due tothe geometry of the fields of view of the motion sensor. 100.

FIG. 4 depicts the 80 fields of view 400 created by the 20 lens elementsand 4 IR-detector elements of an embodiment of a motion sensor 100 suchas shown in FIG. 1B. Each individual lens element directs IR radiationfrom a portion of the scene in front of the motion sensor 100 onto theIR detector 290, so that each element of the IR detector 290 has aunique field of view through each lens. The lenses create multiple tiersof monitored volumes where each tier has multiple rows of monitoredvolumes, such as the two rows per tier that are shown in FIG. 4. In manyembodiments, tiers are substantially non-overlapping and the rows withineach tier are substantially non-overlapping, with the rows within a tiershifted, or offset, from each other so that their monitored volumes arenot vertically aligned with those of other rows within that tier.

In some embodiments, the IR detector array has multiple rows ofIR-detector elements that are offset from each other and the opticalsystem has a set of lenses for each tier. Each individual lens focuseson the entire multi-element surface of IR-detector array, creatingseparate fields of view for each IR-detector element through each lensof each tier. In those embodiments, it can be said that the offsetbetween rows of monitored volumes, or fields of view, is created by theoffset of the rows within the IR-detector array of the motion sensor. Inthe embodiment shown in FIG. 4, the offset between rows of monitoredvolumes, or fields of view, within each tier is created by the offset233 of the two rows of IR-detector elements 212, 216 with the lenses inthe optical system 110, 120, 130 each projecting onto the entire fourIR-detector element surface of the IR detector array 290.

In other embodiments, the IR detector array has multiple rows ofIR-detector elements that are substantially aligned with each other, andthe optical system has a set of lenses for each row within each tier.Each individual lens focuses on a single row of IR-detector elements ofthe IR-detector array, creating separate fields of view for eachIR-detector element within a single row through the lenses focused onthat row within each tier. Each row's lenses are configured to create anoffset between the fields of view of that row and the fields of view ofother rows within a tier. In those embodiments, it can be said that theoffset between rows of monitored volumes, or fields of view, is createdby the configuration of the optical system of the motion sensor.

The top tier of 36 long-range volumes 410 is created by the long-rangenine-lens array 110 projecting onto the four IR-detector elements on theIR-detector array 290. The nine-lens array 110 has a center of viewangled down from the centerline of the motion sensor 100 by about 7°,and the 9 lenses of the array 110 are configured so that theirindividual centers-of-view have a pitch (i.e. centerline-to-centerlineangle) of about 10° to cover an arc of about 90°. The middle tier of 28mid-range volumes 420 is created by the mid-range seven-lens array 120projecting onto the four IR-detector elements on the IR-detector array290. The seven-lens array 120 has a center of view angled down from thecenterline of the motion sensor 100 by about 23°, and the 7 lenses ofthe array 120 are configured so that their individual centers-of-viewhave a pitch of about 13° to cover an arc of about 90°. The bottom tierof 16 short range volumes 430 is created by the short-range four-lensarray 130 projecting onto the four IR-detector elements on theIR-detector array 290. The four-lens array 130 has a center of viewangled down from the centerline of the motion sensor 100 by about 42°,and the 4 lenses of the array 130 are configured so that theirindividual centers-of-view have a pitch of about 23° to cover an arc ofabout 90°. Note that in some embodiments, the motion sensor 100 itselfwill be mounted with its centerline at an angle below horizontal asdiscussed in published International Patent Application WO2015/187326A1.So if the motion sensor is mounted at an angle of 5° below horizontal,that angle is added to the vertical angle of each tier so that, in theembodiment shown, the long-range nine-lens array 110 is aimed 12° belowhorizontal, the mid-range seven-lens array 120 is aimed 28° belowhorizontal, and the short-range four-lens array 130 is aimed 47° belowhorizontal.

Other embodiments may use different optics and/or different IR detectorswith different characteristics to create the rows of monitored volumesoffset from each other such as those disclosed in publishedInternational Patent Application WO2015/088470A1. In embodiments thenumber of tiers may be based on the size of the desired volume ofinterest. For example, an embodiment for a motion sensor targeting a 33ft (10 m) square volume of interest might use 5 sets of lenses to create5 tiers of monitored volumes to keep the height and width of eachmonitored volume at the target height small enough that a human wouldintersect two monitored volumes as they move through the differentportions of the volume of interest, but large enough that a medium-sizeddog would only intersect a single monitored volume.

The number of lenses for each tier in some embodiments is selected toavoid having fields of view in adjacent tiers that are verticallyaligned. The starting azimuth for the first field of view of each tiermay differ in some embodiments to avoid aligned fields of view at theedges of the volume of interest. This may be combined with an adjustmentof the horizontal pitch angle in some embodiments to ensure the finalfields of view of the tiers are not aligned either. In some embodiments,adjacent tiers are created using lens arrays where the number of lensesin an array has no common factors with the number of lenses in anadjacent array. In some embodiments, each array of lenses has a numberof lenses that shares no common factors with the number of lenses in anyother array. This type of arrangement means that a row of monitoredvolumes in one tier shares only a common factor of 2 with a row ofmonitored volumes in another tier. In the embodiment shown, the firstlens array 110 has 9 lenses, which is a multiple of 3, the second lensarray 120 has 7 lenses, which is a prime number, and the third lensarray 130 has 4 lenses, which is multiple of 2, so there are no commonfactors between the numbers of lenses in respective arrays.

At least one embodiment of a motion sensor 100 includes an infrareddetector 290, as shown in FIG. 2D, comprising a first set of detectorelements 212, a second set of detector elements 216, and an opticalsystem that includes multiple subsections 110, 120, 130. A first opticalsubsystem 110 is included to direct infrared radiation from a first setof monitored volumes 410A spaced at a first pitch in a first directiononto the first set of detector elements 212, and to direct infraredradiation from a second set of monitored volumes 410B spaced at thefirst pitch in the first direction and offset from the first set ofmonitored volumes 410A in the first direction, onto the second set ofdetector elements 216. The first set 410A and the second set 410B eachconsist of a first number of monitored volumes. A second opticalsubsystem 120 is also included to direct infrared radiation from a thirdset of monitored volumes 420A spaced at a second pitch in the firstdirection onto the first set of detector elements 212, and to directinfrared radiation from a fourth set of monitored volumes 420B spaced atthe second pitch in the first direction and offset from the third set ofmonitored volumes 420B in the first direction, onto the second set ofdetector elements 216. The third set 420A and the fourth set 420B eachconsist of a second number, different than the first number, ofmonitored volumes. A third optical subsystem 130 is also included todirect infrared radiation from a fifth set of monitored volumes 430Aspaced at a third pitch in the first direction onto the first set ofdetector elements 212, and to direct infrared radiation from a sixth setof monitored volumes 430B spaced at the third pitch in the firstdirection and offset from the fifth set of monitored volumes 430B in thefirst direction, onto the second set of detector elements 216. The fifthset 430A and the sixth set 430B each consist of a third number,different than the second number and the first number, of monitoredvolumes.

FIGS. 5A and 5B show the fields of view 400 of the motion sensor 100intersecting with the volume of interest 320 of FIG. 4. The views 500A,500B are along the motion sensor's 100 pointing axis, diagonal acrossthe room, which is about 28′ (8.5 m). The volume of interest 320, shownin cross-section is where persons are most likely to be moving and thefields of view 400 of the motion sensor 100 cover the various portionsof the volume of interest 320. FIG. 5A shows the three tiers ofmonitored volumes, the top tier of long-range volumes 410, the middletier of mid-range volumes 420, and the bottom tier of short-rangevolumes 430, intersecting the volume of interest 320.

FIG. 5B shows black vertical bars indicating the height of a monitoredvolume created by a single field of view out of the 80 fields of view400 of the motion sensor 100 at particular points in the volume ofinterest 320. The geometry of the fields of view 300 create a relativelyconsistent field of view size in the room to so that there is consistentdetection of minor motion throughout the volume of interest 320 due tothe different focal lengths of the lens arrays 110, 120, 130. Note thatas the longer range fields of view descend into the volume of interest320, the monitored volumes created by those fields of view get larger tohave nearly the same height as the short-range fields of view near themotion sensor 100.

FIG. 6 shows a top view of the fields of view 300 shown in FIG. 2emanating from the motion sensor 100. The long-range fields of view 310are above the mid-range fields of view 320 which are above theshort-range fields of view 330. A cross-section line 7:7 indicates alocation about 5 ft (1.5 m) from the motion sensor 100 perpendicular tothe pointing axis of the motion sensor 100.

FIG. 7 shows a comparison of the fields of view 700 (solid fill), shownin cross section at the line 7:7 of FIG. 6, compared to conventionalmotion sensor fields of view 710 (hashed fill). Note that the fields ofview 600 of the embodiments described herein are smaller higher in theroom and larger lower in the room due to the differing focal lengths ofthe optics compared to the conventional fields of view 710, which are ofa more uniform size at various heights due to uniform focal lengths ofthe optics. This allows the fields of view 700 to start small but asthey radiate further out and down from the motion sensor 100, theyexpand in size to provide for more consistent detection of motion. Theconventional fields of view 710 have many wasted fields of view, as theyare aimed higher than the ceiling. The disclosed fields of view 700 packmore fields of view into the volume of interest.

FIG. 8A shows sensitive minor motion detection by the fields of view700, which are the fields of view 300 shown in cross section at the line7:7 of FIG. 6. Both FIGS. 8A and 8B show the long-range fields of view810 are located above the mid-range fields of view 820 which are locatedabove the short-range fields of view 830. As the distance from themotion sensor 100 increases, the short-range fields of view 830 will nolonger intersect with the volume of interest, and the mid-range fieldsof view 820 and long-range fields of view 810 will descend into thevolume of interest, and grow larger to cover the volume of interest. Atlonger ranges, the mid-range fields of view 820 will no longer intersectwith the volume of interest, and only the long-range fields of view 810will intersect with the volume of interest.

The motion sensor 100 can be used for minor-motion occupancy detection.Each field of view collects IR radiation and directs it onto a detectorelement. A “spot” of radiation, such as the first spot 842 or the secondspot 844, from any main area of a human body, moving either into our outof any field of view, causes a temperature change on the IR-detectorelement and a change in the corresponding output signal, which is usedfor occupancy detection.

FIG. 8B shows pet-immune motion detection by the fields of view 700,which are the fields of view 300 shown in cross section at the line 7:7of FIG. 6. A spot of IR radiation 852 caused by a pet, such as a cat ora dog, can only cause signals from a single field of view. Unlike indetection of occupancy, the spot of IR radiation 852 falling on a singlefield of view is not treated as detecting intrusion.

The spot of IR radiation 854 is caused by a human, which has enoughheight to intersect with two fields of view. This can be used to detectboth occupancy and intrusion. The offset 860 between adjacent rows offields of view can be used to differentiate between human motion andmany sources of false alarms, as will be described in more detail below.

FIG. 9 shows a block diagram of an embodiment of a motion sensor 100.The motion sensor 100 includes an infrared detector 290 that has a firstset of detector elements and a second set of detector elements. Themotion sensor 100 also includes an optical system 904 to directelectromagnetic energy 906 from a first set of monitored volumes ontothe first set of detector elements and to direct electromagnetic energy908 from a second set of monitored volumes onto the second set ofdetector elements. In embodiments, the electromagnetic energy directedonto the detector elements includes infrared light. The first set ofmonitored volumes is spaced at a pitch, and the second set of monitoredvolumes is spaced at the same pitch. The second set of monitored volumeshas an offset from the first set of monitored volumes in a directionparallel to the pitch. In some embodiments the optical system 904creates the offset between the two sets of monitored volumes, and insome embodiments the offset between the two sets of monitored volumes iscreated by an offset between the two sets of detector elements on theinfrared detector 290. The offset can be any percentage of the pitch,depending on the embodiment, but in some embodiments, the offset is anon-quadrature offset, e.g. the offset is not equal to 50% of the pitch.In some embodiments, the motion sensor 100 includes an ambient lightsensor 909. The ambient light sensor 909 may have a separate windowthrough the case of the motion sensor 100 or may have light from theoptical system 904 directed to it.

The motion sensor 100 of the embodiment of FIG. 9 also includescircuitry 910 such as a processor 911 coupled to the infrared detector290 and the ambient light sensor 909 if it is included. Memory 912,which can store computer code 920, is coupled to the processor 911 inembodiments, and the processor 911 can read the computer code 920 fromthe memory 912 and execute the computer code 920 to perform one or moreof the methods described herein in some embodiments.

A wireless network interface 914 is coupled to an antenna 916 as well asto the processor 911 to allow radio frequency messages to be sent and/orreceived by the motion sensor 100 over a wireless computer network suchas, but not limited to, a Wi-Fi® network, a 6LoWPAN network, aBluetooth® network, a Thread network, a Z-Wave® network, or a Zigbee®network. Other embodiments include different types of circuitry 910 thatmay or may not include a processor 911, but may include specializedhard-wired or specialized circuitry to perform one or more methodsdescribed herein. In at least one embodiment, a EFM32ZG110F32 integratedcircuit (IC) from Silicon Laboratories, Inc.® is used, which includes aEFM32® Wonder Gecko MCU utilizing ARM® Cortex®-M0+ 32-bitmicrocontroller and 32 kilobytes (kB) of flash memory and 2 kb of randomaccess memory (RAM), along with an NXP® JN5168 ZigBee and IEEE® 802.15.4wireless microcontroller IC with a 32-bit RISC (reduced instruction setcomputing) CPU, 256 kB of flash memory, and 32 kB RAM. In thisembodiment, the ARM microcontroller and the RISC CPU together constitutethe processor 911, and the flash memory and RAM of both parts togetherconstitute the memory 912. Wi-Fi is a registered trademark of the Wi-FiAlliance, Bluetooth is a registered trademark of the Bluetooth SpecialInterest Group, Z-Wave is a registered trademark of Sigma Designs, Inc.,Zigbee is a registered trademark of the Zigbee Alliance, SiliconLaboratories Inc., and EFM32 are registered trademarks of SiliconLaboratories, Inc., ARM and Cortex are registered trademarks of ARMHoldings, IEEE is a registered trademark of The Institute of Electricaland Electronic Engineers, Inc., and NXP is a registered trademark of NXPSemiconductors.

FIG. 10 is a high level data flow diagram for the motion sensor 100. TheIR detector 290 and the light sensor 909 are physical hardware devicesthat include one or more electronic circuit elements. The front-endprocessing block 1020, occupancy-detection processing block 1030,intrusion detection processing block 1040 and motion sensor-managementblock 1050 may be implemented in any combination of hardware andsoftware, depending on the embodiment. In at least one embodiment, thefront-end processing block 1020 is integrated with the IR detector 290in a single package and the occupancy-detection processing block 1030,intrusion-detection processing block 1040 and motion sensor-managementblock 1050 are implemented using executable code running on one or moreprocessors in the motion detector 100. In one embodiment, a singleprocessor executes code for the occupancy-detection processing block1030, intrusion-detection processing block 1040, and motion-sensormanagement block 1050. In another embodiment, the occupancy-detectionprocessing block 1030 and the intrusion-detection processing block 1040are implemented using code running on a first processor, such as the ARMprocessor of the EFM32ZG110F32 IC, and the motion sensor managementblock 1050 is implemented using code running on a second processor, suchas the RISC CPU of the JN5168 IC.

As is also shown in the block diagram of FIG. 9, the motion sensorincludes an IR detector 290 which has four IR-detector elements coupledto two output channels. The first output channel includes thermalinformation from a first set of monitored volumes, and the second outputchannel includes thermal information from a second set of monitoredvolumes. In at least one embodiment, the first set of monitored volumesincludes the top row 310A of the long-range volumes 310, the top row320A of the mid-range volumes 320, and the top row 330A of the shortrange volumes 330, and the second set of monitored volumes includes thebottom row 310B of the long-range volumes 310, the bottom row 320B ofthe mid-range volumes 320, and the bottom row 330B of the short-rangevolumes 330, which are all shown in FIG. 3. In a more generalized case,the first set of monitored volumes includes alternating rows of themonitored volumes of the motion sensor 100, such as the even rows, andthe second set of monitored volumes has the interleaved rows, such asthe odd rows.

The two output channels from the motion sensor provide data to thefront-end processing block 1020 where they may be filtered in the analogand/or digital domain using high-pass filters, low-pass filters,band-pass filters, notch filters, or any other type of filter, sampledat a digital sample rate to convert the analog signal to a stream ofdigital samples, sample rate converted, converted into the frequencydomain, processed in the frequency domain, converted back to the timedomain, or otherwise processed in the analog or digital domain using anyapplicable signal processing technique. In at least one embodiment, thefront-end processing 1020 subjects the analog signal from each channelof the IR detector to an analog low pass filter to remove frequencieshigher than one half of an intended sample rate and sends the output ofthat filter to an Analog to Digital Converter (ADC) to sample the analogsignals at that sample rate to convert the low-pass filtered IR detectorchannel signals to digital representations. In some embodiments, thefront-end processing block 1020, such as the low-pass filter and ADC,may be integrated into the same package as the IR detector. The outputof the front-end processing block 1020 is then sent to theoccupancy-detection processing block 1030 and/or the intrusion-detectionprocessing block 1040.

Occupancy-detection processing 1030 is enabled by the geometry of themonitored volumes created by the asymmetric tiers of optics of themotion sensor 100 and the offset pairs of IR detector elements of the IRdetector 290 to cover the volume of interest in a room. The front-endprocessed channels of the IR detector 290 are passed from the front-endprocessing block 1020 to the occupancy detection processing block 1030.In some embodiments, the two channels of processed information from theIR detector 290 are mixed together, or summed, after the front-endprocessing 1020 at the input of the occupancy-detection processing block1030, and the single mixed channel is further processed. In otherembodiments, the two channels are processed independently and theirdetection determination combined using a Boolean OR function. Theoccupancy-detection processing 1030 may include any type of processingto determine a change in IR radiation received in either channel,including conversion between the analog and digital domain, sample rateconversion, sample rounding or truncation, analog and/or digitalfiltering including high pass filters, low pass filters, band-passfilters, notch filters, or any other type of filter, conversion betweenthe time domain and frequency domain, or otherwise processed in theanalog or digital domain using any applicable signal processingtechnique. In at least one embodiment, the two channels are separatelyprocessed using one or more high pass filters followed by one or morelow pass filters. The output of the filtered channels is then comparedto a pre-determined threshold and the results of the two channels ORedtogether to determine if the room is occupied. The occupancydetermination made by the occupancy-detection processing block 1030 isthen sent to the motion sensor management block 1050.

Intrusion-detection processing 1040 is also enabled by the geometry ofthe monitored volumes created by the asymmetric tiers of optics of themotion sensor 100 and the offset pairs of IR detector elements of the IRdetector 290 to cover the volume of interest in a room. The front-endprocessed channels of the IR detector 290 are passed from the front-endprocessing block 1020 to the intrusion-detection processing block 1040.In at least some embodiments, the two channels are independentlyprocessed by the intrusion-detection processing block 1040 using anytype of signal processing, including conversion between the analog anddigital domain, sample rate conversion, sample rounding or truncation,analog and/or digital filtering including high-pass filters, low-passfilters, band-pass filters, notch filters, or any other type of filter,conversion between the time domain and frequency domain, or otherwiseprocessed in the analog or digital domain using any applicable signalprocessing technique. In at least one embodiment, the two channels areseparately processed using one or more high pass filters, followed byone or more low-pass moving average filters and then a high-pass filterto compensate for the frequency response of the IR detector 290. Thenthe output of the two channels are compared to determine if a large heatsource, e.g. a human, has been detected, which can be interpreted to bean intrusion determination. An intrusion determination is then sent bythe intrusion-detection processing block 1040 to the motion sensormanagement block 1050. In embodiments, the intrusion-detectionprocessing 1040 is designed to minimize typical passive IR detectorfalse-trigger sources. Various embodiments may utilize any combinationof the disclosed processing methods.

In some embodiments, the intrusion-detection processing 1040 comparesthe two filtered channels by using a two-channel peak-alternation methodto differentiate between a human and a small animal. A two-channelpeak-alternation method can be implemented in many different ways, butit is a method that looks at a predetermined number of sequential peaks,both local minimums and local maximums, in the two input channels, anddetermines that a large warm body has been detected if at least apredetermined portion of the predetermined number of sequential peakswere alternating between the two channels.

In some embodiments, the intrusion-detection processing 1040 comparesthe two filtered channels using peak-slope synchrony test to furtherdifferentiate between a human and a small animal. A peak-slope synchronytest can be implemented in many different ways but it compares the slopeof one channel to the slope of the other channel during a peak-to-peaktime of one of the channels. If the slopes differ by more than apre-determined factor, that is an indicator that the heat source may notbe a large heat source, such as a human. The indicator can be used onits own in some embodiments for intrusion detection, but in otherembodiments, the indication is used in conjunction with two-channelpeak-alternation method, such as being used to decrement a counterkeeping track of the number of alternating peaks.

The motion-sensor management block 1050 receives the indications fromthe occupancy-detection processing block 1030 and theintrusion-detection processing block 1040 and determines what action themotion sensor 100 should take. In some embodiments, the motion sensor100 includes a light sensor 909 to detect ambient light levels which arethen reported to the motion sensor management block 1050. The motionsensor management block 1050 may be configured using messages receivedthrough a network interface of the motion sensor 100, and/or through oneor more input devices on the motions sensor 100, such as switches,dials, sliders, and the like. The configuration may include one or moresettings, such as settings to enable/disable occupancy detection,enable/disable intrusion detection, enable/disable animal/humandifferentiation, determine which intrusion detection method(s) are used,enable/disable ambient light detection, and/or control any other aspectof the operation of the motion sensor 100. The motion sensor managementblock 1050 can then determine how to respond to the various indicationsfrom the occupancy-detection processing 1030, intrusion-detectionprocessing 1040, and light sensor 909. Responses can include, but arenot limited to, reporting on occupancy status, reporting on ambientlight status, intrusion alarm notification, and other responsesdepending on the embodiment. Various mechanisms, in any combination, canbe used by various embodiments for the responses, including, but notlimited to, sending messages over a wired, wireless, or power-linenetwork, activating an audio indicator such as a siren or a recordingplayed over a speaker, activating an optical indicator such as a floodlight, strobe light, or LED, opening or closing a switch coupled to anexternal circuit, or any other way of responding.

FIG. 11 shows a signal-processing diagram for an embodiment of theoccupancy detection processing block 1030. The signal processing shownin FIG. 11 is targeted at a specific embodiment having an IR detectorwith specific properties, an optical system with specific properties,and a processor with particular capabilities. Other embodiments may varysignificantly in the details of the signal processing and may usedifferent bit resolutions and/or data formats, different parameters forthe filters, different filters, or different processing altogether tocondition the signals from the front-end processing block 1120 toprepare them for occupancy detection.

In the embodiment shown, the front end processing block 1120 providestwo channels of digital data at 14 bits per sample with a value of 2000hexadecimal (h) representing about 0 volts. Depending on the embodiment,the two channels may be individually processed as shown in FIG. 11 orthey may be combined, added, or averaged to create a single channel ofdata which is then processed as shown in FIG. 11. In the embodimentshown, each channel is individually processed, but because theprocessing of the two channels is equivalent, the discussion herein willonly address a single channel.

The 14-bit output samples from the front-end processing block 1020 areprovided about every 10 milliseconds (ms) (i.e. 100 Hertz) to anexponential average high-pass filter 1131 using a 6-bit shift leading to−3 decibel (dB) cut-off frequency (hereafter simply referred to as acut-off frequency) of 0.25 Hertz (Hz). The exponential-average high-passfilter 1131 of this embodiment actually utilizes an exponential averagelow-pass filter to filter the stream of samples provided at the input tothe filter block 1131, and the low-pass filtered input is thensubtracted from the input stream, with a baseline input added to itbecause the input is unsigned, to create the high-pass filtered output.Although the 6-bit shift would have the potential to generate a 20-bitresult from the 14-bit input samples, the output is truncated back to 14bits to keep the stream at a meaningful resolution.

The output of the exponential high-pass filter 1131 is then sent throughanother exponential high-pass filter 1132, which in this embodiment isidentical to the first exponential high-pass filter 1131. This is doneto sharpen the low-frequency roll-off of the signal. The output of thesecond exponential high-pass filter 1132, output 1133, is then sent asinput to an exponential average low-pass filter 1136 using a 2-bit shiftleading to a cut-off frequency of 4 Hz. The output of the low-passfilter 1136 is sent to the second low-pass filter 1138, which in thisembodiment is identical to the first low-pass filter 1136. In thisembodiment, the additional two bits of output resolution of the twolow-pass filters 1136, 1138 are kept, providing a 16-bit sample to thesecond low-pass filter 1138 which then outputs an 18-bit sample as theoutput 1139. The effect of the signal processing is to generate aband-pass filtered version of the IR detector channel between about 0.25Hz and about 4 Hz.

The output 1139 is then compared against a predetermined threshold todetermine whether the volume of interest monitored by the motion sensor100 is occupied or not. If the output 1139 is greater than thepredetermined threshold, an occupancy indication is sent to the motionsensor management block 1050. If the second channel of the IR detectoris processed separately, there can be two different sources for theoccupancy indication, one from each channel's processing. Thepredetermined threshold for a particular embodiment can depend on manydifferent factors including the electrical noise in the system, thesensitivity of the IR detector, and the desired sensitivity fordetection of occupancy by the motion sensor, but in at least oneembodiment, the predetermined threshold is about 00060h (as an 18-bitnumber).

FIG. 12 shows a signal processing diagram for an embodiment of theintrusion-detection processing block 1040. The signal processing shownin FIG. 12 is targeted at a specific embodiment having an IR detectorwith specific properties, an optical system with specific properties,and a processor with particular capabilities. Other embodiments may varysignificantly in the details of the signal processing and may usedifferent bit resolutions and/or data formats, different parameters forthe filters, different filters, or different processing altogether tocondition the signals from the front-end processing block 1020 toprepare them for intrusion detection.

In the embodiment shown, the front end processing block 1020 providestwo channels of digital data at 14 bits per sample with a value of 2000hrepresenting about 0 volts. The two channels both are individuallyprocessed as shown in FIG. 12, but because the processing of the twochannels is equivalent, the discussion herein will only address a singlechannel.

The 14-bit output samples from the front-end processing block 1020 areprovided about every 10 ms to an exponential average high-pass filter1241 using an 8-bit shift leading to a cut-off frequency of 0.06 Hz. Theexponential average high-pass filter 1241 of this embodiment actuallyutilizes an exponential average low-pass filter to filter the stream ofsamples provided at the input to the filter block 1241, and the low-passfiltered input is then subtracted from the input stream, with a baselineinput added to it because the input is unsigned, to create the high-passfiltered output. Although the 8-bit shift would have the potential togenerate a 22-bit result from the 14-bit input samples, the output istruncated back to 14 bits to keep the stream at a meaningful resolution.

The output of the exponential high-pass filter 1241 is then sent throughanother exponential high-pass filter 1242, which in this embodiment isidentical to the first exponential high-pass filter 1241. This is doneto sharpen the low-frequency roll-off of the signal. The output of thesecond exponential high-pass filter 1242, output 1243, is then sent asinput to a moving-average low-pass filter 1244 using 4 samples for theaverage leading to a cut-off frequency of 5.6 Hz. A moving averagelow-pass filter is used because it tends to smooth the waveform ascompared to an exponential-average filter. The output of the low-passfilter 1244 has 16 bits which is sent at that resolution to a secondmoving-average low-pass filter 1245, which in this embodiment isidentical to the first moving-average low-pass filter 1244 other thanbecause it takes 16-bit input samples, it has an 18-bit output.

The output of the second low-pass filter 1245 is then sent to anexponential-average high-pass filter 1246 using a 3-bit shift leading toa 2 Hz cut-off frequency. Because the input to this filter 1246 is 18bits, the output is truncated to 18 bits. The purpose of the exponentialhigh pass filter 1246 is to compensate for the frequency response of theIR detector of this embodiment, which rolls off as frequency increases.Very low frequency response, near the 0.06 Hz cut-off frequency of thehigh-pass filters 1241, 1242 earlier in the signal-processing pipeline,is impacted by high-pass filter 1246, so to compensate for that, theoutput of the low-pass filter 1245 is divided by 8 (shifted by 3 bits)by the bypass amplifier 1247 whose output is then added 1248 back to theoutput of the high-pass filter 1246 to create a filtered channel output1249. The effect of this processing is to generate a band-pass filteredversion of the IR detector channel between about 0.06 Hz and about 5.6Hz that has been compensated for the frequency response of the IRdetector to provide a flat response.

The output 1249 for each signal-processing channel is then provided foradditional processing to determine whether or not a human is passingthrough the fields of view of the motion detector, which can beinterpreted as an intrusion. FIG. 13 and FIG. 14A-C provide embodimentsfor analyzing the two channels of filtered IR detector output fordetecting an intruder, i.e. a human, without generating an intrusionindication for movements of pets, such as cats and dogs.

FIG. 13 is a flow chart 1300 of an embodiment of a peak-alternationmethod for intrusion detection. The method shown in flow chart 1300 istargeted for use in a motion sensor using an IR detector with aplurality of outputs, such as the IR detector 290 shown in FIG. 2 whichhas two outputs. Other embodiments may use an IR detector with more thantwo outputs. Peaks are detected in each of the outputs where peak can bea local minimum or a local maximum. In some embodiments, hysteresis isemployed to detect the peaks, meaning that the voltage of the signalmust retreat from the local maximum/minimum by a predetermined amount,which can be an absolute value or a percentage of the maximum/minimum,before a peak is determined. The peak determination may be done by aseparate process running on the CPU, or may be integrated with the codefor performing the method of flow chart 1300.

A set of peaks in the plurality of outputs of the IR detector areselected and an alternation score is calculated based on a number ofalternating peaks in the set of peaks. An intrusion detection isindicated, based, at least in part, on the alternation score. The methodof flowchart 1300 uses a moving window to select the last N peaks forevaluation. The evaluation counts the number of peaks of the last Npeaks that were on a different channel than the previous peak tocalculate an alternation score. If the alternation score is M orgreater, an intrusion detection is indicated to the motion sensormanagement block 1050. The values of N and M can be any number,depending on the embodiment, although M must always be less than N. Insome embodiments, the value for N is between 4 and 20 and the value forM is between 20% and 80% of N. In at least one embodiment, the value forN is 9 and the value for M is 4. Higher values of N mean that theintruder must move within a volume of interest for a longer period oftime to be detected, and lower values of M increase the sensitivity ofthe motion detector to intrusion but also increase the chance for afalse intrusion detection.

The flowchart 1300 starts at block 1301 and then moves to block 1302 toinitialize and fill the first N-1 locations with the channel number ofsuccessive peaks. Once this has been done, the method waits for the nextpeak on any channel at block 1303. Once a peak has been detected, thechannel number of that peak is stored in the Nth buffer location atblock 1304. The buffer is evaluated at block 1305 by counting the numberof locations in the buffer that have a different channel number than theprevious buffer location to determine an alternation score. Otherembodiments can utilize other methods of determining an alternationscore based on a number of alternating peaks in the set of peaks. Thealternation score is compared to a predetermined threshold, M, at block1306. If the alternation score is less than M, the method continues atblock 1307 where each location of the buffer is moved to the previouslocation in the buffer, discarding the oldest peak channel number andleaving room for the next peak channel number to be put into the buffer.The method then goes back to block 1303 to wait for the next peak.

If the alternation score was greater than or equal to M at block 1306,an intrusion detection is indicated at block 1308 to thesensor-management block 1050, which can take whatever action isappropriate based on the configuration of the motion sensor 100. Oncethe intrusion detection has been indicated the method continues byreturning to block 1302 to reinitialize the buffer, but in otherembodiments, the method may go to block 1307 to shift the buffer,leaving the most recent N-1 peak channel numbers in place. Then eitherembodiment will return to block 1303 to wait for the next peak.

FIGS. 14A, 14B, and 14C provide a set of flow charts 1400, 1430, 1460for an embodiment of a peak alternation with slope-synchrony method forintrusion detection. Each of the three flow charts may run as anindependent process on the CPU, along with a process for peak detection,or they may all be integrated into a single process or any number ofindependent processes, depending on the embodiment.

FIG. 14A shows a flow chart 1400 for detecting 6 peaks in the channelsand starts at block 1401. Variables are initialized at block 1402,including setting a PA0 variable, which is used to track a number ofalternating peaks and is used to accumulate the alternation score forthis method, to 0 and setting a PK0 variable, which is used to track anumber of detected peaks, to 0. A timeout variable, Timer0, is alsoinitialized to a timeout value T0 at block 1402. Different embodimentscan utilize different timeout mechanisms. In one embodiment, the Timer0variable is reset to T0 every time that a peak is recognized, so that ifthe gap between any two peaks is more than T0, the Timeout Block 1415forces the method back to block 1402 which reinitializes the variablesand starts the method over again. For embodiments such as these, thetimeout may typically be set in a range of about 1 second (s) to about 5s, depending on the embodiment. In other embodiments, the timeout is setto a time for the entire 6-peak process to complete, which is what isshown in FIG. 14A. So if the entire 6-peak process does not completebefore the timeout period expires, block 1415 forces the method back toblock 1402 which reinitializes the variables and starts the method overagain. For embodiments such as these, the timeout period is longer andmay typically be set in a range of about 5 s to about 20 s, depending onthe embodiment.

After the variables are initialized at block 1402, the method proceedsto block 1403 where it waits until at least one peak has been detectedon each channel. Once a peak has been detected on each channel, the lasttwo detected peaks are evaluated at block 1404 to determine if they areclose enough together that the channels can be considered to be in-phasewith each other. The last two detected peaks are on separate channelsbecause block 1403 was waiting until a peak was detected on bothchannels, so the channel having the last peak had not had a peak before;thus the previous peak was on a different channel. The measure forcloseness may vary depending on the embodiment, but can be a fixed time,or a dynamic time calculated by the motion sensor based on history suchas a percentage of the last peak-to-peak period of one of the channels,which may also be referred to as an interpeak period. If it isdetermined that the two peaks are close together, the method returns toblock 1402 to reinitialize variables and start over.

If the two peaks are determined to not be too close to each other atblock 1404, the method continues to block 1405 where the PA0 variable isincremented because the two pulses were known to be alternating, asdescribed above, and the PK0 variable is set to 2 because two pulseshave been detected. The method then continues to block 1406 to wait forthe next peak.

Once a peak is detected at block 1406, it is checked to see if the peakis on a different channel than the previous peak at block 1407. If thepeak is on a different channel, the PA0 variable and the PK0 variableare both incremented by one at block 1408 because a new peak wasdetected and it was alternating. If the peak was on the same channel asthe previous peak, the PA0 variable is decremented by one and the PK0variable is incremented by one at block 1409, because a peak wasdetected but it was not alternating, so a penalty is imposed on thealternation score. In the case where two peaks are detected at the samesampling time, the PA0 variable is left unchanged, and the PK0 counteris incremented by 2 at block 1410 because it is unclear in what orderthe two peaks actually occurred. Once the PA0 variable and the PK0variable have been updated, the PK0 variable is checked at block 1411.If the PK0 variable is less than six, the method returns to block 1406to wait for the next peak.

If, however, the PK0 variable is greater or equal to six, the method mayoptionally proceed to block 1412 before continuing to block 1413. Block1412 is a synchronization block to ensure that the slope-synchronycalculation process shown in flowchart 1460 has completed its post-peakprocessing before continuing. Not all embodiments includeslope-synchrony calculation, so those embodiments would skip block 1412.Some embodiments may integrate the slope-synchrony calculation methodwith the 6-peak detection method, so those embodiments would also skipblock 1412 as no synchronization is necessary.

Once it is known that the slope-synchrony calculation process 1460 hascompleted its post-peak processing or there is no need for synchronizingwith a slope-synchrony calculation process 1460, the PA0 variable ischecked at block 1413. If that variable is not greater than zero, nointrusion detection will be indicated at this time, so the methodcontinues to block 1402 to reinitialize variables and start over. If,however, PA0 is greater than zero, the method continues to block 1414where the value of PA0 is transferred to PA1, the value of PK0 istransferred to PK1, and the 3-peak detection process of flowchart 1430is started before the method of flowchart 1400 proceeds to block 1402where its variables are reinitialized and the 6-peak detection processstarts over.

FIG. 14B shows a flow chart 1430 for detecting 3 peaks in the channelsand starts at block 1431 with its PA1 and PK1 variable pre-initializedby the 6-peak detection process shown in flow chart 1400. In someembodiments, the method continues to block 1432 where a separate timeris initialized for the 3-peak detection process. The value of the timemay vary between embodiments, but it may be set between about 3 secondsand about 10 seconds in some embodiments. If the Timer1 timeout expiresbefore the 3-peak detection method of flow chart 1430 is completed,block 1444 will end the process at block 1443. In some embodiments, ifthe timeout from the 6-peak detection process 1400 expires, it may alsoend the 3-peak detection process 1430.

After the timer has been initialized at block 1432, the method proceedsto block 1433 to wait for the next peak. Note that because the 3-peakdetection process 1430 and the 6-peak detection process 1400 runconcurrently, any peak detected by the 3-peak detection process willalso be detected by the 6-peak detection process. Once a peak has beendetected at block 1433, it is checked to see if the peak is on adifferent channel than the previous peak at block 1434. If the peak ison a different channel, the PA1 variable and the PK1 variable are bothincremented by one at block 1435 because a new peak was detected and itwas alternating. If the peak was on the same channel as the previouspeak, the PA1 variable is decremented by one and the PK1 variable isincremented by one at block 1436, because a peak was detected but it wasnot alternating, so a penalty is imposed on the alternation score. Inthe case where two peaks are detected at the same sampling time, the PA1variable is left unchanged and the PK1 counter is incremented by 2 atblock 1437 because it is unclear in what order the two peaks actuallyoccurred. Once the PA1 variable and the PK1 variable have been updated,the PK1 variable is checked at block 1438. If the PK1 variable is lessthan nine, which includes peaks detected by the previous 6-peakdetection process 1400 and the current 3-peak detection process 1430,the method returns to block 1433 to wait for the next peak.

If, however, the PK1 variable is greater or equal to nine, the methodmay optionally proceed to block 1439 before continuing to block 1440.Block 1439 is a synchronization block to ensure that the slope-synchronycalculation process shown in flowchart 1460 has completed its post-peakprocessing before continuing. Not all embodiments includeslope-synchrony calculation, so those embodiments would skip block 1439.Some embodiments may integrate the slope-synchrony calculation method1460 with the 3-peak detection method 1430, so those embodiments wouldalso skip block 1439 as no synchronization is necessary.

Once it is known that the slope-synchrony calculation process 1460 hascompleted its post-peak processing, or there is no need forsynchronizing with a slope-synchrony calculation process 1460, the PA1variable is checked at block 1440. If that variable is less than four,no intrusion detection will be indicated at this time, so the methodterminates at block 1443.

If the PA1 variable is greater than or equal to four, the methodcontinues to block 1441 where an intrusion detection is indicated to themotion-sensor management block 1050 to take appropriate action, althoughin some embodiments the 3-peak detection process 1430 may directly takethe intrusion response action, such as sending a message over a network,sounding an alarm, and/or turning on lights. Once the intrusionnotification has been provided, in some embodiments, the 6-peakdetection method of flow chart 1400 and/or the slope-synchronycalculation method of flow chart 1460 are reset and restarted at block1442 before the 3-peak detection method is terminated at block 1443.

In some embodiments, if a timeout, which may be from Timer0 of the6-peak detection process, or Timer1 of the 3-peak detection process,occurs, the 3-peak detection process may evaluate PK1 and PA1 todetermine if an intrusion notification should be indicated. In at leastone embodiment, if a timeout occurs before PK1=9, then the 3-peakdetection method proceeds to block 1441 to send the intrusionnotification if PK1=8 and PA1≥4, PK1=7 and PA1≥3, or PK1=6 and PA1≥3.

Note that there are several items that can be varied to tune performanceof the 6-peak detection process 1400 and the 3-peak detection process1430, including the value that PK0 is compared to in block 1411, whichdetermines how many peaks to find in the 6-peak detection process 1400and the value that PK1 is compared to in block 1438 of the 3-peakdetection process 1430, which determines how many peaks total are to befound before evaluating for intrusion detection. Other items that can betuned include the value that PA0 is compared to in block 1413 of the6-peak detection process 1400 to determine whether or not to launch the3-peak process, the value that PA1 is compared to in block 1440 todetermine whether or not to indicate an intrusion detection once thetotal number of evaluated peaks have been detected, and the values usedto determine whether or not to indicate an intrusion if a timeout occursbefore the 3-peak process completes.

FIG. 14C shows a flow chart 1460 for an embodiment of a slope synchronycalculation method which starts at block 1461. Variables are initializedto zero at block 1462 and then the method waits for one of three events.A 50 ms period is waited on at block 1463, although other embodimentsmay use a different waiting period that is longer or shorter than 50 ms.Some embodiments may utilize the same waiting period as the sample rateof the incoming channels from the IR detector. Every 50 ms the methodcontinues to block 1464 where the voltage changes of the channels areaccumulated. In the embodiment show, four accumulators are managed. Thefirst accumulator, VT00 accumulates the absolute values of the change involtage of channel 0 during a peak-to-peak period of channel 0, and thesecond accumulator, VT01, accumulates the absolute values of the changein voltage of channel 0 during a peak-to-peak period of channel 1. Thethird accumulator, VT10 accumulates the absolute values of the change involtage of channel 1 during a peak-to-peak period of channel 0, and thefourth accumulator, VT11, accumulates the absolute values of the changein voltage of channel 1 during a peak-to-peak period of channel 1. Oncethe accumulators have been updated, the current voltage of each channelis saved as the previous voltage of the respective channel before themethod returns to block 1463 to wait for the end of another 50 msperiod.

The method 1460 also waits for a peak to be detected on channel 0 atblock 1465. In response to a peak on channel 0, the method proceeds toblock 1466 where the accumulated voltage changes of the two channelsduring the peak-to-peak period of channel 0 are compared. Because thetime that the changes have been accumulated over is the same for bothchannels, the ratio of the accumulated voltage changes is equal to theratio of the slopes. In one embodiment, a ratio of VT10 to VT00 iscalculated and compared to a predetermined slope ratio (PSR). If theratio is between PSR and 1/PSR, the slopes of the channels are insynchrony for that time period, and the peak alternation variables, PA0,PA1, are not modified. If, however, the ratio of VT10 to VT00 is notbetween PSR and 1/PSR, the slopes of the channels are not in synchronyso the alternation score is modified by decrementing PA0 and PA1, whicheffectively cancels any effect of an alternation for that peak. Beforereturning to block 1465 to wait for the next peak on channel 0, theaccumulators used for the channel 0 peak-to-peak accumulation, VT10 andVT00, are both reset to 0 to start accumulating for a new channel 0peak-to-peak period. In some embodiments, a penalty count is keptinstead of directly modifying the alternation score, and the penaltycount is used with the alternation score to determine whether toindicate an intrusion after the desired number of peaks has beendetected.

The method 1460 also waits for a peak to be detected on channel 1 atblock 1467. In response to a peak on channel 1, the method proceeds toblock 1468 where the accumulated voltage changes of the two channelsduring the peak-to-peak period of channel 1 are compared. Because thetime that the changes have been accumulated over is the same for bothchannels, the ratio of the accumulated voltage changes is equal to theratio of the slopes. In one embodiment, a ratio of VT11 to VT01 iscalculated and compared to a predetermined slope ratio (PSR). If theratio is between PSR and 1/PSR, the slopes of the channels are insynchrony for that time period, and the peak-alternation variables, PA0,PA1 are not modified. If, however, the ratio of VT11 to VT01 is notbetween PSR and 1/PSR, the slopes of the channels are not in synchronyso the alternation score is modified by decrementing PA0 and PA1, whicheffectively cancels any effect of an alternation for that peak. Beforereturning to block 1467 to wait for the next peak on channel 1, theaccumulators used for the channel 1 peak-to-peak accumulation, VT11 andVT01, are both reset to 0 to start accumulating for a new channel 1peak-to-peak period.

Various embodiments may use differing values for PSR, depending on thesensitivity of the IR detector, the signal processing performed, andvarious other factors. Some embodiments may use a PSR between about 1.5and 5. In at least one embodiment, however, the PSR is about 3.

The method 1460 determines a peak-to-peak period for a first output ofthe plurality of outputs of the IR detector by looking for peaks onchannel 0 and having separate accumulators, VT00 and VT10, of thevoltage change for the two channels that are used over the channel 0peak-to-peak period and are reset every time a new peak is detected onchannel 0. The method 1460 also calculates a slope-synchrony measurementbased on a first average slope of the first output over said period anda second average slope of a second output of the plurality of outputs ofthe IR detector over said period by calculating a ratio of VT10 to VT00for the channel 0 peak-to-peak period. The method 1460 modifies thealternation score based, at least in part, on the slope-synchronymeasurement by decrementing PA0 and/or PA1. This means that indicatingan intrusion detection is based, at least in part, on both theslope-synchrony measurement and the alternation score in method 1460.

Another embodiment of the slope-synchrony method starts looking at thechannels when the 6-peak method 1400 starts up and at a slope-samplinginterval TSS, records the absolute value of the voltage change inchannel 0 |ΔVCH0| and channel 1 |ΔVCH1| since the last slope samplinginterval. As each channel's first signal peak since the method startedis detected, the average of each channel's ΔV is calculated from thestart of the method until peak-detection time, and a peak slope ratio iscalculated as the average of |ΔVCH0| divided by the average of |ΔVCH1|and checked to see if it is between a fixed constant PSR value and itsreciprocal. If it is not, then the current peak as disqualified byincrementing a Penalty Counter (PC) by one (from zero, if on the firstpeak, or otherwise from its current value). Then, until each channel'snext new peak is detected, the embodiment continues to record |ΔVCH0|and |ΔVCH1| from that channel's previous peak-detection time until thenext peak-detection time. When that channel's next new peak is detected,the average of each channel's ΔV from that channel's previouspeak-detection time until the present peak-detection time is computed,and a peak-slope ratio is calculated as the average of |ΔVCH0| dividedby the average of |ΔVCH1| and checked to see if it is between the fixedconstant PSR value and its reciprocal. If it is not, then the currentpeak as disqualified by incrementing PC by one. When the PK counterreaches full count or when the detection-process timeout is reached, thePC value is subtracted from the PA-counter value, then the resulting PAvalue is used as in the other embodiments for determining intrusiondetection or no detection.

FIG. 15 and FIG. 16 are images from an oscilloscope showing thetwo-channel output of an IR detector in response to a human and ananimal, respectively, moving through the volume of interest. This datawas collected from experiments using a prototype motion sensor similarto those described herein. The prototype motion sensor includes an IRdetector similar to the IR detector shown in FIG. 2A-D which includes afirst set of detector elements 212 coupled to a first output channel ofthe IR detector and a second set of detector elements 216 coupled to asecond output channel of the IR detector. Front-end processing isperformed inside of the IR detector so that 14-bit digital samples fromboth channels are sent through a single physical connection out of theIR detector. The prototype motion sensor also includes thehigh-resolution triple-lens array shown in FIG. 1A which includes along-range lens array 110 with a center of view angled down about 7°from the centerline of the prototype motion sensor, a mid-range lensarray 120 with a center of view angled down about 23° from thecenterline of the prototype motion sensor, and a short-range lens array130 with a center of view angled down about 42° from the centerline ofthe prototype motion sensor. The prototype motion sensor was mountedabout 8 ft (2.4 m) from the floor with its centerline tilted down about5° from horizontal.

The long-range lens array 110 can be considered a first opticalsubsystem designed to direct infrared radiation from a first set of ninemonitored volumes 410A onto the first set of detector elements 212. Thenine monitored volumes are distributed approximately evenly horizontallythrough about a 90° range, which determines a first pitch of about 10°,in the horizontal direction. The first optical subsystem also isdesigned to direct infrared radiation from a second set of ninemonitored volumes 410B, spaced at the first pitch in the horizontaldirection and offset from the first set of monitored volumes 410A in thehorizontal direction, onto the second set of detector elements 216. Inthe prototype motion sensor, the first set of monitored volumes 410A ispositioned above the second set of monitored volumes 410B.

The mid-range lens array 120 can be considered a second opticalsubsystem designed to direct infrared radiation from a third set ofseven monitored volumes 420A onto the first set of detector elements212. The seven monitored volumes are distributed horizontallyapproximately evenly through about a 90° range, which determines asecond pitch of about 13° in the horizontal direction. The secondoptical subsystem also is designed to direct infrared radiation from afourth set of seven monitored volumes 420B, spaced at the second pitchin the horizontal direction and offset from the third set of monitoredvolumes 420A in the horizontal direction, onto the second set ofdetector elements 216. In the prototype motion sensor, the second set ofmonitored volumes 410B is positioned above the third set of monitoredvolumes 420A which is positioned above the fourth set of monitoredvolumes 420B.

The short-range lens array 130 can be considered a third opticalsubsystem designed to direct infrared radiation from a fifth set of fourmonitored volumes 430A onto the first set of detector elements 212. Thefour monitored volumes are distributed horizontally approximately evenlythrough about a 90° range, which determines a third pitch of about 23°in the horizontal direction. The third optical subsystem also isdesigned to direct infrared radiation from a sixth set of four monitoredvolumes 430B, spaced at the third pitch in the horizontal direction andoffset from the fifth set of monitored volumes 430A in the horizontaldirection, onto the second set of detector elements 216. In theprototype motion sensor, the fourth set of monitored volumes 420B ispositioned above the fifth set of monitored volumes 430A which ispositioned above the sixth set of monitored volumes 430B.

The prototype motion sensor includes a first system-on-chip (SoC), anEFM32ZG110F32 from Silicon Laboratories, Inc., coupled to the IRdetector to receive both output channels. The first SoC includescomputer code to implement the occupancy-detection processing block 1030as shown in FIG. 11A/B and the intrusion-detection processing block 1040as shown in FIG. 12A/B and FIG. 14A-C. The prototype motion sensor alsoincludes a second SoC, a JN5168 from NXP, coupled to the first SoC andto the ambient light detector 909. The second SoC includes a wirelessnetwork interface and computer code to implement the motion sensormanagement block 1050.

FIG. 15 is an image from an oscilloscope showing the two-channel outputof an IR detector in response to a human moving through the volume ofinterest. The first trace 1510, shown as a solid line, represents thesignal from a first channel (Ch0) of the IR detector, and the secondtrace 1520, shown as a broken line, represents the second channel (Ch1)of the IR detector. The traces 1510, 1520 were captured at a sweep rateof 250 milliseconds (ms) per division.

As was mentioned above, the prototype motion sensor use a two-channelpeak alternation method for intrusion detection to minimize false alarmscaused by small warm-blooded animals, such as cats, dogs and birds. Theprototype motion sensor identifies an intruder's motion by thealternating peaks of the IR detector's two signals from itsspatially-offset fields of view. When a human walks through the fieldsof view, two phase-offset signals are produced with alternating peaks,as shown by Ch0 1510 and Ch1 1520 in the image 1500.

Table 1 below shows some of the events from the Ch0 1510 and Ch1 1520and shows how the method shown in FIG. 14A-C processes those events. Thefirst column is simply a row number and the “Event” column identifies anevent on the image 1500, such as a peak in one of the channels. The“Alt?” column indicates whether the peak was an alternate peak ascompared to the previous peak. The “P2P Period” column identifies theperiod of time used by the slope-synchrony process 1460 to use todetermine if the slopes of the two channels are in synchrony. The “SlopeSync?” column indicates whether the slope-synchrony process 1460determined that the slopes were in synchrony and whether or not thealternation score is adjusted. The “PK0”, “PA0”, “PK1”, and “PA1”columns provide the value of the respective variables in the 6-peakprocess 1400 and 3-peak process 1430 after they have been adjusted forthe peak included in that row, and the “Int?” column indicates whetheran intrusion detection notification is sent.

Table 1 starts at row 1 with Restart 1501 which came after a restart ofthe 6-peak process 1400 which can be either block 1401 or block 1402.The slope-synchrony process 1460 is also restarted at restart 1501. Thenext event is peak 1511 on Ch0, shown on row 2, which is evaluated bythe slope-synchrony process 1460 over the peak-to-peak period of Ch01501-1511, and it is determined that the slopes of the two channels werein synchrony during that period, so no adjustment of the alternationscore is necessary. PK0 and PA0 are unchanged by the 6-peak process asit is still waiting for the second peak at block 1403.

Row 3 of Table 1 shows that a peak 1522 was detected on Ch1, which is analternate peak and is the 2nd peak seen by the 6-peak process 1400 whichthen sets PK0 to 2 and increments PA0 by 1. The slope-synchrony process1460 evaluates the change in voltage of the two channels over the periodfrom peak 1501 to peak 1522 and determines that the two channels are insynchrony so no adjustment to the alternation score is necessary.Because this particular set of traces stays in synchrony for the entireperiod, the slope-synchrony process 1460 will not be discussed furtherfor these traces 1510, 1520.

Row 4 of Table 1 shows that alternating peak 1513 on Ch0 was recognizedand both the PK0 and PA0 variables incremented. Row 5 of Table 1 showsthat peak 1514 was recognized on Ch0, which is not an alternating peakbecause the previous peak was also on Ch0. In response to recognizing anon-alternating peak, PK0 is incremented to 4, but PA0 is decrementedback down to 1.

TABLE 1 Event Alt? P2P Period Slope Sync? PK0 PA0 PK1 PA1 Int? 1 1501Restart — — — 0 0 — — No 2 1511 Ch0 Peak — 1501-1511 Sync No PA Adj. 0 0— — No 3 1522 Ch1 Peak Yes 1501-1522 Sync No PA Adj. 2 1 — — No 4 1513Ch0 Peak Yes 1511-1513 Sync No PA Adj. 3 2 — — No 5 1514 Ch0 Peak No1513-1514 Sync No PA Adj. 4 1 — — No 6 1525 Ch1 Peak Yes 1522-1525 SyncNo PA Adj. 5 2 — — No 7 1516 Ch0 Peak Yes 1514-1516 Sync No PA Adj. 6/03/0 6 3 No 8 1527 Ch1 Peak Yes 1525-1527 Sync No PA Adj. 0 0 7 4 No 91518 Ch0 Peak Yes 1516-1518 Sync No PA Adj. 2 1 8 5 No 10 1529 Ch1 PeakYes 1527-1529 Sync No PA Adj. 3 2 9 6 Yes 11 1509 Restart — — — 0 0 — —No

Row 6 and row 7 of Table 1 both show detection of alternating peaks1525, 1516 which both cause the PK0 and PA0 variables to be incremented.PK0 is set to 6 at block 1408 and checked at block 1411 in the 6-peakprocess 1400, so the value of PA0 is checked at block 1413 where thevalue of PA0, which was set to 3 at block 1408, is found to be greaterthan 0. Therefore, the 3-peak process 1430 is launched with PK1 set to 6and PA1 set to 3, the values of PK0 and PA0 respectively, at block 1414before PK0 and PA0 are reset to 0 at block 1402 and the 6-peak process1400 restarts.

Row 8 of Table 1 shows the detection of peak 1527 on Ch0, which is analternate peak, causing the 3-peak process 1430 to increment both PK1and PA1 while the 6-peak process 1400 continues to wait for the secondpeak. Peak 1518 is shown in row 9 of Table 1 causing the 6-peak process1400 to set PK0 to 2 and PA0 to 1 while the 3-peak process 1430increments PK1 to 8 and PA1 to 5.

Row 10 of Table 1 shows that peak 1529 on Ch1 was detected causing the6-peak process 1400 to increment PK0 to 3 and PA0 to 2 while the 3-peakprocess 1430 increments PK1 to 9 and PA1 to 6. The 3-peak process 1430detects that PK1 is 9 at block 1438 and checks PA1 at block 1440, whichis greater than 4, causing an intrusion detection to be sent at block1441 of the 3-peak process 1430 before the 6-peak process 1400 and theslope-synchrony process 1460 are restarted and the 3-peak process endedat block 1443, as shown in line 11 of Table 1. Note that while the twochannels stayed in synchrony during the traces 1510, 1520 shown in theimage 1500, even if the slope-synchrony process 1460 had determined thatduring some of the peak-to-peak periods the two channels' slopes wereout of synchrony, the intrusion detection would have still occurred aslong as it only happened during one or two peak-to-peak periods.

FIG. 16 is an image from an oscilloscope showing the two-channel outputof an IR detector in response to a small animal moving through thevolume of interest. The first trace 1610, shown as a solid line,represents the signal from a first channel (Ch0) of the IR detector, andthe second trace 1620, shown as a broken line, represents the secondchannel (Ch1) of the IR detector. The traces 1610, 1620 were captured ata sweep rate of 250 milliseconds (ms) per division.

As was mentioned above, the prototype motion sensor uses a two-channelpeak alternation method for intrusion detection to minimize false alarmscaused by small warm-blooded animals, such as cats, dogs, and birds. Theprototype motion sensor differentiates small animal motion from anintruders' motion by detecting that consecutive peaks are on the samechannel, not alternating as the channels do for human detection. Butsome movements by animals through the monitored space create complexwaveforms that can be interpreted as having alternate peaks as is shownin the image 1600.

Table 2 below shows some of the events from the Ch0 1610 and Ch1 1620and shows how the method shown in FIG. 14A-C processes those events. Thefirst column is simply a row number, and the “Event” column identifiesan event on the image 1600, such as a peak in one of the channels. The“Alt?” column indicates whether the peak was an alternate peak ascompared to the previous peak. The “P2P Period” column identifies theperiod of time used by the slope-synchrony process 1460 to use todetermine if the slopes of the two channels are in synchrony. The “SlopeSync?” column indicates whether the slope-synchrony process 1460determines that the slopes were in synchrony and whether or not thealternation score is adjusted. The “PK0”, “PA0”, “PK1”, and “PA1”columns provide the value of the respective variables in the 6-peakprocess 1400 and 3-peak process 1430 after they have been adjusted forthat peak, and the “Int?” column indicates whether an intrusiondetection notification is sent.

Table 2 starts at row 1 with Timeout 1601 which causes a restart of the6-peak process 1400 at block 1402. The slope-synchrony process 1460 isalso restarted at timeout 1601. The next event is peak 1611 on Ch0,shown on row 2, which is evaluated by the slope-synchrony process 1460over the peak-to-peak period of Ch0 1601-1611, and it is determined thatthe slopes of the two channels were in synchrony during that period, sono adjustment of the alternation score is necessary. PK0 and PA0 areunchanged by the 6-peak process as it is still waiting for the secondpeak at block 1403.

TABLE 2 Event Alt? P2P Period Slope Sync? PK0 PA0 PK1 PA1 Int? 1 1601Timeout — — — 0 0 — — No 2 1611 Ch0 Peak — 1601-1611 Sync No PA Adj. 0 0— — No (1^(st) Pk) 3 1622 Ch1 Peak Yes 1601-1622 Sync No PA Adj. 2 1 — —No 4 1613 Ch0 Peak Yes 1611-1613 No Sync Adj. PA 3 +1 − 1 = 1 — — No 51624 Ch1 Peak Yes 1622-1624 No Sync Adj. PA 4 +1 − 1 = 1 — — No 6 1615Ch0 Peak Yes 1613-1615 No Sync Adj. PA 5 +1 − 1 = 1 — — No 7 1626 Ch1Peak Yes 1624-1626 No Sync Adj. PA 6/0  +1 − 1 = 1/0 6 1 No 8 1617 Ch0Peak Yes 1615-1617 No Sync Adj. PA 0 −1 7 +1 − 1 = 1 No (1^(st) Pk) 91628 Ch1 Peak Yes 1626-1628 Sync No PA Adj. 2 0 8 2 No 10 1619 Ch0 PeakYes 1617-1619 Sync No PA Adj. 3 1 9 3 No 11 1634 Ch0 Peak No 1619-1634No Sync Adj. PA 4 −1  — — No 12 1635 Ch0 Peak No 1634-1635 No Sync Adj.PA 5 −3  — — No 13 1646 Ch1 Peak Yes 1628-1646 No Sync Adj. PA 6/0    +1− 1 = −3/0 — — No

Row 3 of Table 2 shows that a peak 1622 was detected on Ch1, which is analternate peak and is the 2nd peak seen by the 6-peak process 1400 whichthen sets PK0 to 2 and increments PA0 by 1. The slope-synchrony process1460 evaluates the change in voltage of the two channels over the periodfrom peak 1601 to 1622 and determines that the two channels are insynchrony so no adjustment to the alternation score is necessary. Row 4of Table 2 shows that alternating peak 1613 on Ch0 was recognized andboth the PK0 and PA0 variables are incremented at block 1408 of the6-peak process 1400. But the slope-synchrony process 1430 determinesthat the two channels' slopes were not in synchrony during the 1611-1633peak-to-peak period of Ch0, so PA0 is decremented at block 1465 of theslope-synchrony process 1460, leaving PA0 at 1.

Rows 5, 6 and 7 of Table 2 all show detection of alternating peaks 1624,1615, 1626 without slope synchrony, which causes the PK0 variable to beincremented each time, but also causes the PA0 variable to beincremented by the 6-peak process 1400 and decremented by theslope-synchrony process 1460 for each peak 1624, 1615, 1626, leaving PA0at 1. PK0 is set to 6 at block 1408 in the 6-peak process 1400, so block1411 detects that, and the 6-peak process 1400 then evaluates PA0 atblock 1413. Because the value of PA0 is 1, which is greater than 0, the3-peak process 1430 is launched with PK1 set to 6 and PA1 set to 1, thevalues of PK0 and PA0 respectively, at block 1414 before PK0 and PA0 arereset to 0 at block 1402 and the 6-peak process 1400 restarts.

Row 8 of Table 2 shows the detection of peak 1617 on Ch0, which is analternate peak, causing the 3-peak process 1430 to increment both PK1and PA1 while the 6-peak process 1400 continues to wait for the secondpeak at block 1403, so the 6-peak process 1400 does not change PK0 orPA0. The slopes of the channels are determined to not be in sync duringthe 1615-1617 peak-to-peak period of Ch0, so PA1 and PA0 are decrementedby the slope-synchrony process 1430. Peak 1628 is shown in row 9 ofTable 2 causing the 6-peak process to set PK0 to 2 and increment PA0 to0 while the 3-peak process 1430 increments PK1 to 8 and PA1 to 2. Thetwo channels are determined to be in synchrony, so there is noadjustment of PA0 or PA1 by the slope-synchrony process 1460.

Row 10 of Table 2 shows that peak 1619 was detected on Ch0. Because peak1619 is an alternate peak and the two channels' slopes were insynchrony, PK0, PA0, PK1, and PA1 are all incremented. PK1 is determinedto be equal to 9 at block 1438 of the 3-peak process 1430, causing PA1to be evaluated at block 1440. Because PA1 is less than 4, no intrusiondetection is indicated, and the 3-peak process 1430 ends at block 1443.

Row 11 and 12 of Table 2 show peak 1634 and peak 1635 on Ch0 which areboth non-alternating peaks, and the two channels' slopes are determinedto not be in synchrony for both peak-to-peak periods, causing PA0 to bedecremented twice for each peak, once at block 1409 of the 6-peakprocess 1400 and once at block 1436 of the slope-synchrony process 1460.Peak 1646 on Ch1 in row 13 of Table 2 is an alternating peak, but thetwo channels are not in synchrony, so PA0 is incremented anddecremented, leaving PA0 at −3. PK0 is set to 6 so PA0 is evaluated todetermine whether or not to launch a 3-peak process. PA0 is −3, which isless than 0, so the 3-peak process is not launched and PK0 and PA0 arereset back to 0 and the 6-peak process 1400 restarts.

Other test cases were also created for an animal moving through thevolume of interest where one channel had peaks while the other channelhad no peaks or where the first channel had several peaks followed bythe other channel having several peaks. A person having ordinary skillin the art can easily follow the flow charts 1400, 1430, 1460 to seethat no intrusion detection would be generated in those cases, avoidinga false intrusion notification. Testing of the prototype motion sensorhas shown a very low false alarm rate while at the same time showing agood sensitivity to intrusion by a human. The prototype motion sensorhas also shown a high sensitivity to motion for generating occupancydetection notifications when used for that purpose. Thus, motion sensorsbuilt as described herein can function as both an effective occupancydetector as well as a sensitive intrusion detector with a lowfalse-alarm rate.

Aspects of various embodiments are described with reference to flowchartillustrations and/or block diagrams of methods, apparatus, systems, andcomputer program products according to various embodiments disclosedherein. It will be understood that various blocks of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

The flowchart and/or block diagrams in the figures help to illustratethe architecture, functionality, and operation of possible embodimentsof systems, devices, methods, and computer program products of variousembodiments. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment, or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems or circuitry that perform thespecified functions or acts, or combinations of special purposehardware, circuitry, and computer instructions.

As will be appreciated by those of ordinary skill in the art, aspects ofthe various embodiments may be embodied as a system, device, method, orcomputer program product apparatus. Accordingly, aspects of the presentinvention may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, resident software,micro-code, or the like) or an embodiment combining software andhardware aspects that may all generally be referred to herein as a“server,” “circuit,” “module,” “client,” “computer,” “logic,” or“system.” Furthermore, aspects of the various embodiments may take theform of a computer program product embodied in one or more computerreadable medium(s) having computer program code stored thereon.

Any combination of one or more computer readable storage medium(s) maybe utilized. A computer readable storage medium may be embodied as, forexample, an electronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or other like storagedevices known to those of ordinary skill in the art, or any suitablecombination of computer readable storage mediums described herein. Inthe context of this document, a computer readable storage medium may beany tangible medium that can contain, or store a program and/or data foruse by or in connection with an instruction execution system, apparatus,or device.

Computer program code for carrying out operations for aspects of variousembodiments may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++, or the like, and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The computer program code if loaded onto acomputer, or other programmable apparatus, produces a computerimplemented method. The instructions which execute on the computer orother programmable apparatus may provide the mechanism for implementingsome or all of the functions/acts specified in the flowchart and/orblock diagram block or blocks. In accordance with variousimplementations, the program code may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).The computer program code stored in/on (i.e. embodied therewith) thenon-transitory computer readable medium produces an article ofmanufacture.

The computer program code, if executed by a processor causes physicalchanges in the electronic devices of the processor which change thephysical flow of electrons through the devices. This alters theconnections between devices which changes the functionality of thecircuit. For example, if two transistors in a processor are wired toperform a multiplexing operation under control of the computer programcode, if a first computer instruction is executed, electrons from afirst source flow through the first transistor to a destination, but ifa different computer instruction is executed, electrons from the firstsource are blocked from reaching the destination, but electrons from asecond source are allowed to flow through the second transistor to thedestination. So a processor programmed to perform a task is transformedfrom what the processor was before being programmed to perform thattask, much like a physical plumbing system with different valves can becontrolled to change the physical flow of a fluid.

Examples of various embodiments are described below:

Embodiment 1. A method of detecting motion using an infrared detectorwith a plurality of outputs, the method comprising:

selecting a set of peaks in the plurality of outputs of the infrareddetector;

calculating an alternation score based on a number of alternating peaksin the set of peaks; and

indicating motion detection based, at least in part, on the alternationscore.

Embodiment 2. The method of embodiment 1, wherein the indicatingcomprises sounding an audible intrusion alarm or turning on one or morelights.

Embodiment 3. The method of any of embodiments 1-2, wherein theindicating comprises sending a message over a network, contents of themessage dependent upon settings in a motion sensor that includes theinfrared detector, the contents including an occupancy status, ananimal-immune intrusion indication, or a non-animal-immune motiondetection indication.

Embodiment 4. The method of any of embodiments 1-3, further comprisingband-pass filtering the plurality of outputs of the infrared detectorbefore said selecting.

Embodiment 5. The method of embodiment 4, wherein the band-passfiltering has a band-pass range of about 0.25 Hz to about 4 Hz.

Embodiment 6. The method of embodiment 4, further comprisingcompensating the plurality of outputs of the infrared detector for afrequency response of the infrared detector before said selecting.

Embodiment 7. The method of embodiment 6, wherein the band-passfiltering has a band-pass range of about 0.06 Hz to about 5.6 Hz.

Embodiment 8. The method of any of embodiments 1-7, the set of peaksconsisting of a predetermined number of consecutive peaks in theplurality of outputs of the infrared detector.

Embodiment 9. The method of any of embodiments 1-8, further comprising:

determining a peak-to-peak period for a first output of the plurality ofoutputs of the infrared detector;

calculating a slope-synchrony measurement based on a first average slopeof the first output over said period and a second average slope of asecond output of the plurality of outputs of the infrared detector oversaid period; and

modifying the alternation score based, at least in part, on theslope-synchrony measurement.

Embodiment 10. A method of detecting motion using an infrared detectorwith a plurality of outputs, the method comprising:

determining a peak-to-peak period for a first output of the plurality ofoutputs of the infrared detector;

calculating a slope-synchrony measurement based on a first average slopeof the first output over said period and a second average slope of asecond output of the plurality of outputs of the infrared detector oversaid period; and

indicating motion detection based, at least in part, on theslope-synchrony measurement.

Embodiment 11. The method of embodiment 10, wherein the indicatingcomprises sounding an audible intrusion alarm or turning on one or morelights.

Embodiment 12. The method of any of embodiments 10-11, wherein theindicating comprises sending a message over a network, contents of themessage dependent upon settings in a motion sensor that includes theinfrared detector, the contents including an occupancy status, ananimal-immune intrusion indication, or a non-animal-immune motiondetection indication.

Embodiment 13. The method of any of embodiments 10-12, furthercomprising band-pass filtering the plurality of outputs of the infrareddetector before said determining.

Embodiment 14. The method of embodiment 13, wherein the band-passfiltering has a band-pass range of about 0.25 Hz to about 4 Hz.

Embodiment 15. The method of embodiment 13, further comprisingcompensating the plurality of outputs of the infrared detector for afrequency response of the infrared detector before said determining.

Embodiment 16. The method of embodiment 15, wherein the band-passfiltering has a band-pass range of about 0.06 Hz to about 5.6 Hz.

Embodiment 17. The method of any of embodiments 10-16, wherein thecalculating of the slope-synchrony measurement comprises:

accumulating absolute values of discrete changes in voltage of the firstoutput from a first peak in the first output to a second peak in thefirst output;

accumulating an absolute value of discrete changes in voltage of thesecond output from the first peak in the first output to the second peakin the first output; and

calculating a ratio between the accumulated changes in the first outputand the accumulated changes in the second output as the slope-synchronymeasurement.

Embodiment 18. The method of any of embodiments 10-17, furthercomprising:

selecting a set of peaks in the plurality of outputs of the infrareddetector;

calculating an alternation score based on a number of alternating peaksin the set of peaks; and

indicating the motion detection based, at least in part, on thealternation score.

Embodiment 19. A method of detecting motion comprising:

receiving a first output of an infrared detector representing a warmbody passing through a first set of monitored volumes;

receiving a second output of the infrared detector representing the warmbody passing through a second set of monitored volumes, wherein thesecond set of monitored volumes have a horizontal offset from the firstset of monitored volumes;

detecting first peaks of the first output and second peaks of the secondoutput;

determining an evaluation period;

creating an alternation score based on a relative phase relationship ofthe first peaks to the second peaks during the evaluation period;

generating an animal-immune motion indication based on the alternationscore.

Embodiment 20. The method of embodiment 19, the first set of monitoredvolumes comprising a first row of monitored volumes of a first tier ofmonitored volumes and the second set of monitored volumes comprising asecond row of monitored volumes of the first tier of monitored volumes,the second row of monitored volumes of the first tier of monitoredvolumes horizontally offset from, and non-overlapping with, the firstrow of monitored volumes of the first tier of monitored volumes.

Embodiment 21. The method of embodiment 20, the first set of monitoredvolumes comprising a first row of monitored volumes of a second tier ofmonitored volumes and the second set of monitored volumes comprising asecond row of monitored volumes of the second tier of monitored volumes,the first row of monitored volumes of the second tier of monitoredvolumes horizontally offset from, and non-overlapping with, the secondrow of monitored volumes of the second tier of monitored volumes;

the first tier of monitored volumes created by a first optical subsystemwith a first focal length and consisting of a first number of monitoredvolumes;

the second tier of monitored volumes created by a second opticalsubsystem with a second focal length and consisting of a second numberof monitored volumes;

wherein the first focal length is different than the second focallength, and the first number is different than the second number.

Embodiment 22. The method of any of embodiments 19-21, furthercomprising band-pass filtering the first output of the infrared detectorand the second output of the infrared detector before said detecting.

Embodiment 23. The method of any of embodiments 22-22, furthercomprising compensating the first output of the infrared detector andthe second output of the infrared detector for a frequency response ofthe infrared detector before said detecting.

Embodiment 24. The method of any of embodiments 19-23, furthercomprising:

determining interpeak periods of the first output;

calculating, for the interpeak periods of the first output occurringduring the evaluation period, ratios of first values to second values,the first values based on a slope of the first output and the secondvalues based on a slope of the second output; and

adjusting the alternation score based on the ratios.

Embodiment 25. The method of any of embodiments 19-24, wherein theevaluation period is determined based on a number of combined firstpeaks and second peaks.

Embodiment 26. A method of detecting motion comprising:

receiving a first output of an infrared detector representing a warmbody passing through a first set of monitored volumes;

receiving a second output of the infrared detector representing the warmbody passing through a second set of monitored volumes, wherein thesecond set of monitored volumes have a horizontal offset from the firstset of monitored volumes;

detecting peaks of the first output;

determining interpeak periods of the first output;

determining an evaluation period;

calculating, for the interpeak periods of the first output occurringduring the evaluation period, ratios of first values to second values,the first values based on a slope of the first output and the secondvalues based on a slope of the second output;

generating an animal-immune motion indication based on the ratios.

Embodiment 27. The method of embodiment 26, further comprising band-passfiltering the first output of the infrared detector and the secondoutput of the infrared detector before said detecting.

Embodiment 28. The method of any of embodiments 26-27, furthercomprising compensating the first output of the infrared detector andthe second output of the infrared detector for a frequency response ofthe infrared detector before said detecting.

Embodiment 29. The method of any of embodiments 26-28, the first set ofmonitored volumes comprising a first row of monitored volumes of a firsttier of monitored volumes and the second set of monitored volumescomprising a second row of monitored volumes of the first tier ofmonitored volumes, the second row of monitored volumes of the first tierof monitored volumes horizontally offset from, and non-overlapping with,the first row of monitored volumes of the first tier of monitoredvolumes.

Embodiment 30. The method of embodiment 29, the first set of monitoredvolumes comprising a first row of monitored volumes of a second tier ofmonitored volumes and the second set of monitored volumes comprising asecond row of monitored volumes of the second tier of monitored volumes,the first row of monitored volumes of the second tier of monitoredvolumes horizontally offset from, and non-overlapping with, the secondrow of monitored volumes of the second tier of monitored volumes;

the first tier of monitored volumes created by a first optical subsystemwith a first focal length and consisting of a first number of monitoredvolumes;

the second tier of monitored volumes created by a second opticalsubsystem with a second focal length and consisting of a second numberof monitored volumes;

wherein the first focal length is different than the second focallength, and the first number is different than the second number.

Embodiment 31. A method of detecting motion comprising:

receiving a first output of an infrared detector representing a warmbody passing through a first set of monitored volumes;

receiving a second output of the infrared detector representing the warmbody passing through a second set of monitored volumes, wherein thesecond set of monitored volumes have a horizontal offset from the firstset of monitored volumes;

detecting first peaks of the first output and second peaks of the secondoutput;

during a period where N combined first peaks and second peaks aredetected, creating an alternation score based on a relative phaserelationship of the first peaks to the second peaks;

generating an animal-immune motion indication based on the alternationscore.

Embodiment 32. The method of embodiment 31, further comprising band-passfiltering the first output of the infrared detector and the secondoutput of the infrared detector before said detecting.

Embodiment 33. The method of any of embodiments 31-32, furthercomprising compensating the first output of the infrared detector andthe second output of the infrared detector for a frequency response ofthe infrared detector before said detecting.

Embodiment 34. The method of any of embodiments 31-33, the first set ofmonitored volumes comprising a first row of monitored volumes of a firsttier of monitored volumes and the second set of monitored volumescomprising a second row of monitored volumes of the first tier ofmonitored volumes, the second row of monitored volumes of the first tierof monitored volumes horizontally offset from, and non-overlapping with,the first row of monitored volumes of the first tier of monitoredvolumes.

Embodiment 35. The method of embodiment 34, the first set of monitoredvolumes comprising a first row of monitored volumes of a second tier ofmonitored volumes and the second set of monitored volumes comprising asecond row of monitored volumes of the second tier of monitored volumes,the first row of monitored volumes of the second tier of monitoredvolumes horizontally offset from, and non-overlapping with, the secondrow of monitored volumes of the second tier of monitored volumes;

the first tier of monitored volumes created by a first optical subsystemwith a first focal length and consisting of a first number of monitoredvolumes;

the second tier of monitored volumes created by a second opticalsubsystem with a second focal length and consisting of a second numberof monitored volumes;

wherein the first focal length is different than the second focallength, and the first number is different than the second number.

Embodiment 36. At least one machine readable medium comprising one ormore instructions that in response to being executed on a computingdevice cause the computing device to carry out a method according to anyone of embodiments 1 through 35.

Embodiment 37. A motion sensor comprising:

an infrared detector comprising a first set of detector elements and asecond set of detector elements;

a first optical subsystem adapted to direct infrared radiation from afirst row of monitored volumes spaced at a first pitch in a firstdirection onto the first set of detector elements, and to directinfrared radiation from a second row of monitored volumes spaced at thefirst pitch in the first direction, and offset from the first row ofmonitored volumes in the first direction, onto the second set ofdetector elements, the first row and the second row each consisting of afirst number of monitored volumes; and

a second optical subsystem adapted to direct infrared radiation from athird row of monitored volumes spaced at a second pitch in the firstdirection onto the first set of detector elements, and to directinfrared radiation from a fourth row of monitored volumes spaced at thesecond pitch in the first direction, and offset from the third row ofmonitored volumes in the first direction, onto the second set ofdetector elements, the third row and the fourth row each consisting of asecond number of monitored volumes, the second number being differentthan the first number.

Embodiment 38. The motion sensor of embodiment 37, wherein the onlycommon factor between the first number and the second number is 2.

Embodiment 39. The motion sensor of any of embodiments 37-38, the firstoptical system having a first focal length and the second optical systemhaving a second focal length, the second focal length different than thefirst focal length.

Embodiment 40. The motion sensor of embodiment 39, wherein a ratio ofthe first focal length to the second focal length is about equal to asquare-root of 2.

Embodiment 41. The motion sensor of any of embodiments 39-40, wherein,with the motion sensor in an upright position, the first row ofmonitored volumes is positioned above the second row of monitoredvolumes, the second row of monitored volumes is positioned above thethird row of monitored volumes, and the third row of monitored volumesis positioned above the fourth row of monitored volumes;

the first focal length is longer than the second focal length; and

the first number of monitored volumes is greater than the second numberof monitored volumes.

Embodiment 42. The motion sensor of any of embodiments 39-41, furthercomprising:

a third optical subsystem having a third focal length, different fromthe first focal length and the second focal length, and adapted todirect infrared radiation from a fifth row of monitored volumes spacedat a third pitch in the first direction onto the first set of detectorelements, and to direct infrared radiation from a sixth row of monitoredvolumes spaced at the third pitch in the first direction, and offsetfrom the fifth row of monitored volumes in the first direction, onto thesecond set of detector elements, the fifth row and the sixth row eachconsisting of a third number of monitored volumes, the third numberbeing different than the first number and the second number;

wherein the only common factor between any two of the first number, thesecond number, and the third number is 2.

Embodiment 43. The motion sensor of any of embodiments 37-42, whereinthe second set of detector elements are positioned with a first detectoroffset from the first set of detector elements in a first detectordirection on a pyroelectric substrate; and

the second set of detector elements are positioned at a second detectoroffset from the first set of detector elements in a second detectordirection on the pyroelectric substrate that is orthogonal to the firstdetector direction.

Embodiment 44. The motion sensor of any of embodiments 37-42, whereinthe second set of detector elements are positioned without a significantoffset from the first set of detector elements in a first detectordirection on a pyroelectric substrate, and the second set of detectorelements are positioned at an offset from the first set of detectorelements in a second detector direction on the pyroelectric substratethat is orthogonal to the first detector direction; and

wherein the first optical system comprises:

a first set of optical elements to direct the infrared radiation fromthe first row of monitored volumes onto the first set of detectorelements via a first optical path having a first geometry; and

a second set of optical elements to direct the infrared radiation fromthe second row of monitored volumes onto the second set of detectorelements via a second optical path having a second geometry that isdifferent than the first geometry.

Embodiment 45. The motion sensor of any of embodiments 37-44, furthercomprising:

intrusion detection circuitry, coupled to the first set of detectorelements via a first channel and coupled to the second set of detectorelements via a second channel, the intrusion detection circuitry adaptedto indicate an intrusion detection.

Embodiment 46. The motion sensor of any of embodiments 45, furthercomprising:

a first band-pass filter with a first filter input coupled to a firstoutput of the first set of detector elements and a first filter outputcoupled to the first channel; and

a second band-pass filter with a second filter input coupled to a secondoutput of the second set of detector elements and a second filter outputcoupled to the second channel.

Embodiment 47. The motion sensor of any of embodiments 45-46, furthercomprising:

a first frequency compensation filter with a first compensation inputcoupled to a first output of the first set of detector elements and afirst compensation output coupled to the first channel; and

a second frequency compensation filter with a second compensation inputcoupled a second output of the second set of detector elements and asecond compensation output coupled to the second channel.

Embodiment 48. The motion sensor of any of embodiments 45-47, theintrusion detection circuitry further adapted to:

select a set of peaks in a first signal received via the first channeland in a second signal received via the second channel;

calculate an alternation score based on a number of alternating peaks inthe set of peaks; and

indicate the intrusion detection based, at least in part, on thealternation score.

Embodiment 49. The motion sensor of any of embodiments 45-48, theintrusion detection circuitry further adapted to:

determine a peak-to-peak period for a first signal received via thefirst channel;

calculate a slope-synchrony measurement based on a first average slopeof the first signal over said period and a second average slope of asecond signal received via the second channel over said period; and

indicate the intrusion detection based, at least in part, on theslope-synchrony measurement.

Embodiment 50. The motion sensor of any of embodiments 45-19, theintrusion detection circuitry further adapted to indicate the intrusiondetection by sounding an audible intrusion alarm or turning on one ormore lights.

Embodiment 51. The motion sensor of any of embodiments 45-50, theintrusion detection circuitry further adapted to indicate the intrusiondetection by sending a message over a network, contents of the messagedependent upon settings in the motion sensor, the contents including anoccupancy status, an animal-immune intrusion indication, or anon-animal-immune motion detection indication.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. Thus, for example, reference to an elementdescribed as “a monitored volume” may refer to a single monitoredvolume, two monitored volumes, or any other number of monitored volumes.As used in this specification and the appended claims, the term “or” isgenerally employed in its sense including “and/or” unless the contentclearly dictates otherwise. As used herein, the term “coupled” includesdirect and indirect connections. Moreover, where first and seconddevices are coupled, intervening devices including active devices may belocated there between. Unless otherwise indicated, all numbersexpressing quantities of elements, percentages, and so forth used in thespecification and claims are to be understood as being modified in allinstances by the term “about.” Interpretation of the term “about” iscontext specific, but in the absence of other indications, shouldgenerally be interpreted as ±10% of the modified quantity, measurement,or distance. The recitation of numerical ranges by endpoints includesall numbers subsumed within that range (e.g. 1 to 5 includes 1, 2.78,3.33, and 5). Any element in a claim that does not explicitly state“means for” performing a specified function, or “step for” performing aspecified function, is not to be interpreted as a “means” or “step”clause as specified in 35 U.S.C. § 112(f).

The description of the various embodiments provided above isillustrative in nature and is not intended to limit this disclosure, itsapplication, or uses. Thus, different variations beyond those describedherein are intended to be within the scope of embodiments. Suchvariations are not to be regarded as a departure from the intended scopeof this disclosure. As such, the breadth and scope of the presentdisclosure should not be limited by the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and equivalents thereof.

What is claimed is:
 1. A motion sensor comprising: an infrared detectorcomprising a first set of detector elements and a second set of detectorelements; a first optical subsystem adapted to direct infrared radiationfrom a first row of monitored volumes spaced at a first pitch in a firstdirection onto the first set of detector elements, and to directinfrared radiation from a second row of monitored volumes spaced at thefirst pitch in the first direction, and offset from the first row ofmonitored volumes in the first direction, onto the second set ofdetector elements, the first row and the second row each consisting of afirst number of monitored volumes; and a second optical subsystemadapted to direct infrared radiation from a third row of monitoredvolumes spaced at a second pitch in the first direction onto the firstset of detector elements, and to direct infrared radiation from a fourthrow of monitored volumes spaced at the second pitch in the firstdirection, and offset from the third row of monitored volumes in thefirst direction, onto the second set of detector elements, the third rowand the fourth row each consisting of a second number of monitoredvolumes, the second number being different than the first number.
 2. Themotion sensor of claim 1, wherein the only common factor between thefirst number and the second number is
 2. 3. The motion sensor of claim1, the first optical system having a first focal length and the secondoptical system having a second focal length, the second focal lengthdifferent than the first focal length.
 4. The motion sensor of claim 3,wherein a ratio of the first focal length to the second focal length isabout equal to a square-root of
 2. 5. The motion sensor of claim 3,wherein, with the motion sensor in an upright position, the first row ofmonitored volumes is positioned above the second row of monitoredvolumes, the second row of monitored volumes is positioned above thethird row of monitored volumes, and the third row of monitored volumesis positioned above the fourth row of monitored volumes; the first focallength is longer than the second focal length; and the first number ofmonitored volumes is greater than the second number of monitoredvolumes.
 6. The motion sensor of claim 3, further comprising: a thirdoptical subsystem having a third focal length, different from the firstfocal length and the second focal length, and adapted to direct infraredradiation from a fifth row of monitored volumes spaced at a third pitchin the first direction onto the first set of detector elements, and todirect infrared radiation from a sixth row of monitored volumes spacedat the third pitch in the first direction, and offset from the fifth rowof monitored volumes in the first direction, onto the second set ofdetector elements, the fifth row and the sixth row each consisting of athird number of monitored volumes, the third number being different thanthe first number and the second number; wherein the only common factorbetween any two of the first number, the second number, and the thirdnumber is
 2. 7. The motion sensor of claim 1, wherein the second set ofdetector elements are positioned with a first detector offset from thefirst set of detector elements in a first detector direction on apyroelectric substrate; and the second set of detector elements arepositioned at a second detector offset from the first set of detectorelements in a second detector direction on the pyroelectric substratethat is orthogonal to the first detector direction.
 8. The motion sensorof claim 1, wherein the second set of detector elements are positionedwithout a significant offset from the first set of detector elements ina first detector direction on a pyroelectric substrate, and the secondset of detector elements are positioned at an offset from the first setof detector elements in a second detector direction on the pyroelectricsubstrate that is orthogonal to the first detector direction; andwherein the first optical system comprises: a first set of opticalelements to direct the infrared radiation from the first row ofmonitored volumes onto the first set of detector elements via a firstoptical path having a first geometry; and a second set of opticalelements to direct the infrared radiation from the second row ofmonitored volumes onto the second set of detector elements via a secondoptical path having a second geometry that is different than the firstgeometry.
 9. The motion sensor of claim 1, further comprising: intrusiondetection circuitry, coupled to the first set of detector elements via afirst channel and coupled to the second set of detector elements via asecond channel, the intrusion detection circuitry adapted to indicate anintrusion detection.
 10. The motion sensor of claim 9, furthercomprising: a first band-pass filter with a first filter input coupledto a first output of the first set of detector elements and a firstfilter output coupled to the first channel; and a second band-passfilter with a second filter input coupled to a second output of thesecond set of detector elements and a second filter output coupled tothe second channel.
 11. The motion sensor of claim 9, furthercomprising: a first frequency compensation filter with a firstcompensation input coupled to a first output of the first set ofdetector elements and a first compensation output coupled to the firstchannel; and a second frequency compensation filter with a secondcompensation input coupled a second output of the second set of detectorelements and a second compensation output coupled to the second channel.12. The motion sensor of claim 9, the intrusion detection circuitryfurther adapted to: select a set of peaks in a first signal received viathe first channel and in a second signal received via the secondchannel; calculate an alternation score based on a number of alternatingpeaks in the set of peaks; and indicate the intrusion detection based,at least in part, on the alternation score.
 13. The motion sensor ofclaim 9, the intrusion detection circuitry further adapted to: determinea peak-to-peak period for a first signal received via the first channel;calculate a slope-synchrony measurement based on a first average slopeof the first signal over said period and a second average slope of asecond signal received via the second channel over said period; andindicate the intrusion detection based, at least in part, on theslope-synchrony measurement.
 14. The motion sensor of claim 9, theintrusion detection circuitry further adapted to indicate the intrusiondetection by sounding an audible intrusion alarm and/or turning on oneor more lights.
 15. The motion sensor of claim 9, the intrusiondetection circuitry further adapted to indicate the intrusion detectionby sending a message over a network, contents of the message dependentupon settings in the motion sensor, the contents including an occupancystatus, an animal-immune intrusion indication, and/or anon-animal-immune motion detection indication.
 16. A method of detectingmotion comprising: receiving infrared radiation from a first row ofmonitored volumes spaced at a first pitch in a first direction, thefirst row of monitored volumes consisting of a first number of monitoredvolumes; receiving infrared radiation from a second row of monitoredvolumes spaced at the first pitch in the first direction, and offsetfrom the first row of monitored volumes in the first direction, thesecond row of monitored volumes consisting of the first number ofmonitored volumes; receiving infrared radiation from a third row ofmonitored volumes spaced at a second pitch in the first direction, thethird row of monitored volumes consisting of a second number ofmonitored volumes, the second number being different than the firstnumber; receiving infrared radiation from a fourth row of monitoredvolumes spaced at the second pitch in the first direction, and offsetfrom the third row of monitored volumes in the first direction, thefourth row of monitored volumes consisting of the second number ofmonitored volumes; directing the infrared radiation from the first rowof monitored volumes and the third row of monitored volumes onto a firstset of detector elements of an infrared detector; directing the infraredradiation from the second row of monitored volumes and the fourth row ofmonitored volume onto a second set of detector elements of the infrareddetector; analyzing a first signal generated by the first set ofdetector elements of the infrared detector and a second signal generatedby the second set of detector elements of the infrared detector todetect movement of a warm object through at least a portion of the firstrow, the second row, the third row, and/or the fourth row of monitoredvolumes; and indicating that the movement of the warm object has beendetected.
 17. The method of claim 16, further comprising: filtering thefirst signal with a first frequency compensation filter before theanalyzing; and filtering the second signal with a second frequencycompensation filter before the analyzing.
 18. The method of claim 16,the analyzing comprising: selecting a set of peaks in the first signaland in the second signal; calculating an alternation score based on anumber of alternating peaks in the set of peaks; and determining thatthe movement has been detected based, at least in part, on thealternation score.
 19. The method of claim 16, the analyzing comprising:determining a peak-to-peak period for the first signal; calculating aslope-synchrony measurement based on a first average slope of the firstsignal over said period and a second average slope of the second signalover said period; and determining that the movement has been detectedbased, at least in part, on the slope-synchrony measurement.
 20. Themethod of claim 16, the indicating that the movement has been detectedcomprising sending a message over a network, contents of the messagedependent upon settings in the motion sensor, the contents including anoccupancy status, an animal-immune intrusion indication, and/or anon-animal-immune motion detection indication.